This item has the following downloads:

( PDF )

STATE OF FLORIDA
DEPARTMENT OF CONSERVATION

GEORGE W. DAVIS, Supervisor 9-









GEOLOGICAL BULLETIN NO. 13









OSTRACODA OF THE ARCA ZONE OF THE
CHOCTAWHATCHEE MIOCENE OF FLORIDA


BY
HENRY V. HOWE, Ph.D., Director


School of

School of


Geology, Louisiana State
and graduate students
Geology, Louisiana State


University

University


o, ,' PuI ished for -.
.., %tt'e -Ward of Conser;vatio'
; *Geological Department' *
"o Tallahassee, 1935
S- ,0, 0 0 I
" 3 1 I
;i ~ ~ ~ ~ ~ -. ,-- I -


35


"









































Published S ibr 1th, 193























'ubl)islIcd St'jltta1II~t'I 10th, 1!3


to 0 O 8
.. :"*
*0.* * *
* o **
* t
*.* @


. .0. .0


0* 0 .1

0 4* * I* ** q *,* g


L o I *


S ....". .:: .. *
S . ; : *. *
. 0 '. : .. : ..
04 0 to 0 0 04
4.e.~( *ol ...


,. ot


0





LETTER OF TRANSMITTAL


Honorable George W. Davis,
Supervisor of Conservation.

D)I'An MR. DAVIS:
It gives me pleasure to transmit for publication as Geologi-
cal Bulletin No. 13 a paper by Dr. Henry V. Howc, D)irector,
School of Geology, Louisiana State University, Baton Rouge,
in collaboration with a number of students of that institution,
entitled "Ostracoda of the Arca Zone of the Choctawhatchee
Miocene of Florida." The Florida Survey has published other
reports relating to the invertebrates of the Miocene of western
Florida. This paper by Dr. H-owe and collaborators deals witl
a special group of micro-fossils from a particular zone in 'the
Choctawhatchee formation, namely, the Ostracoda, and is the
first report dealing with this interesting group of fossils in
such a detailed manner from Florida. The fauna of this Area
Zone will therefore now be very thoroughly covered. This
technical paper with its four excellent illustrations colnes
without cost to the Florida Survey other than the expense of
publication. It is a pleasure to acknowledge this generous
contribution and cooperation.
I also wish to express my appreciation of the interest you
have always shown in the work of the Geological Division and
the cordial support rendered.
Very respectfully,
HERMAN GUNTEI, Assistant Supervisor,
State Board of Conservation,
Geological Department.

Tallahassee, Florida.
July 27, 1935.



(31
1


















CONTENTS
PAGE
Introduction 7
List of Stations .. 8
descriptionn of Genera and Species 9



ILLUSTRATIONS
Plates I-IV. Ostracoda of the Area Zone of the Choctaw-
hatchee Miocene of Florida 39


(5]








































































































































































































I





OSTRACODA OF THE ARCA ZONE OF THE
CHOCTAWHATCHEE MIOCENE OF FLORIDA
By HENRY V. HowE and others'
Louisiana State University

INTRODUCTION
In the spring of 1930, Mr. Karl E. Young made an extensive
collecting trip which extended to Florida, and was kind
enough to supply the writer with a large number of' samples
from many of the famous Miocene localities there. During
the Christmas holidays of 1933, the writer accompanied Dr.
Richard J. Russell of the School of Geology, Louisiana State
University, on a collecting trip to Florida and many additional
localities were visited. Later, in the summer of 1934, the
writer spent some ten days in Western Florida, and was ac-
companied by Mr. Merle C. Israelsky, paleontologist for the
United Gas Company, Houston, Texas. Mr. Carroll E. Cook
has also supplied the writer with several samplles of Florida
Miocene material. As a result of these collecting trips, the
writer has had available for study extensive samples from
nearly all of the localities in the Florida Miocene from which
Dr. Joseph A. Cushman and Gerald M. Ponton have described
loraminifera.' As their papers are so widely known and used,
the writer has felt it desirable to arrange his locality list as
nearly in agreement with theirs as possible. With the excep-
tion of Mr. Young's locality near Ward, Florida, the numbers

'This paper is the result of a study made by the author's graduate
class in micropaleontology at Louisiana State University. Each of the
following graduate students has contributed drawings for the plates,
has worked out the finer structures of certain species, and has trins-
lated certain European works on the Ostracoda which have aided in
the study: Jack Chambers, Bates Brown, James McGuirt, Wenzel Neill,
Leo Hough, Albeit D. Ellis, Jr., Morton 'Stephenson, Julia Spurgeon,
Lloyd Pyentt, Christian Dohm, Wade Hadley, Ralph Taylor, and T. J.
Johnson. Their names appear with the senior author's on the new
species which they worked out. The writer wishes to express his ap-
preciation of their enthusiastic assistance in the preparation of this
manusCril)t.
'Cushman, J. A., "The Foraminifera of the Choctawhatchee Forma-
tion of Florida," Fla. Geol. Surv., Bull. No. 4, 1930.
Cushman, J. A. and Ponton, G. M., "The Foraminifera of the Upper,
Middle and a Part of the Lower Miocene of Florida," Fla. Geol. Surv.,
Bull. No. 9, 1932.
[7J





8 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

and descriptions have been taken from Florida Geological
Survey Bulletin No. 9. Only the localities are given from
which species have been described:

LIST OF STATIONS
Sample No. 10.-Tenmile Creek, from bridge to one-half mile below
bridge on the Marianna-Clarksville road, 22 miles south of Marianna,
Calhoun County. Collected by K. E. Young.
Sample No. 14.-U. S. G. S. locality No. 11732.-Borrow-pit just cast
of the power dam at Jackson Bluff on Ocklocknee River, Leon County.
Collected by Carroll E. Cook.
Sample No. 15.-U. S. G. S. locality Nos. 1/671 and 1/947. Jim
Kennedy Branch, one mile east of Red Bay, Walton County. Collected
by H. V. Howe and M. C. Israclsky.
Sample No. 26.-U. S. G. S. locality No. 7054.-At old sawmill near
Oak Grove on right bank of Yellow River about 100 yards below bridge
on Laurel I-ill-Oak Grove road, Okaloosa County. Collected by H. V.
Howe and M. C. Israelsky.
Sample No. 28.-U. S. G. S. locality No. 10608.-Small gully, 50 feet
south of road and 150 feet east of bridge over White's Creek on
Euchecanna-Knox Hill road, one mile west of Valley Church, Walton
County. Collected by H. V. Howe and M. C. Israclsky.
Sample No. 29.-U. S. G. S. locality No. 10659.-Senterflet's or
Tanner's Mill (abandoned), four miles southwest of Laurel Hill,
Okaloosa County. Collected by H. V. Howe and M. C. Israelsky.
Sample No. 31.-U. S. G. S. locality No. 10658.-Toward upper end
of Shell Bluff' on right bank of Shoal River, five miles north of Mossy-
head, Walton County. Collected by K. E. Young, by H-. V. Howe
and i. .1. Russell, and by H. V. Howe and M. C. Israelsky.
K. E. Young Locality No. 34.-Choctawhatchee Miocene, pit of West
Florida Power Company, just east of road at power dam, being about
300 feel east of tie hydro-electric power plant near Ward, Florida,
which is about 26 miles southwest of Tallahassee, on the Ocklocknee
River.
Sample No. 40.-U. S. G. S. locality No. 1/948.-John Anders6n's
farm, three-quarters of a mile east of Red Bay, Wallon County. Collected
by II. V. lowe and M. C. Israelsky.
Sample No. 41.-U. S. G. S. locality Nos. 1/673 and 1/950.-At small
spring head in E. Gomillion's field at Red Bay, Wallon County. Col-
lected by II. V. Howe and M. C. Israelsky.

This paper deals essentially with the ostracodes obtained
at Localities Nos. 15, 40 and 41. Locality No. 40 is considered
to be ihe type locality of the Choclawhatchcc formation, and
lie three localities all belong to the Arca zone of the forma-
lion, and have quite similar assemblages. This zone was se-
lected for study, both because it was the type horizon of the
Choclawhatchee, and because it was very difficult to separate
it from the underlying Yoldia zone and from the Shoal River
formation on the basis of foraminifera. Both the Arca zone
and the Shoal River contain abundant ostracodes and the
present study has definitely established that these assemblages
are so distinct that they may be easily separated. In this




CHOCTAWHATCHIIEE OSTRACODA OF THE ARCA ZONE 9

paper, an attempt has been made to describe or to call atten-
tion to such species of the Shoal River as might be confused
with those of' the Arca zone. A few of the species that range
above or below the Area zone have been described from
younger or older formations in case they were found to have
better preservation at these stations. In every case the known
vertical range of' each species is given.
As the only extensive previous paper dealing with American
Miocene oslracodes was the excellent one published by Ulrich
and Bassler' in Maryland Geological Survey, an(d as their types
lare preserved in tlie National Museum, the writer, through the
courtesy of' Dr. R. J. Russell, obtained some nineteen samples
of' material from Plum Point, Maryland, their most important
locality. When this material liad been studied, he took his
collections to Washington and compared the species herein
described with Ulrich and Bassler's types, which were kindly
placed at his disposal by Dr. Basslcr. The writer, therefore,
feels that in extending the range of a number of species from
Maryland to Florida, he has done so with safely.
In conclusion the writer wishes to express his appreciation
of' the assistance given hiin by Mr. Morton Stcphenson in tihe
assembling of' the plates which accompany the paper, and he
particularly wishes to thank Miss Louise Lowc, Librarian of
the School of Geology, Louisiana State University, who prc-
pared and catalogued the type specimens, and who cheerfully
ldevote(d so much of her time to tlie assembling and final check-
ing of' the manuscript.

DESCRIPTION OF GENERA AND SPECIES
Order OSTRACOIA Latreille
Suborder PODOCOP)A Snrs
Family CYTHERIDAE Baird
Genus CYT'HERI)EA Bosquel
C(ytheridea choclawhatcheensis Howe and Stelhenson, n. sp.
Plate II, figure 11; Plate IV, figure 9.
Carapace small, subovate, smooth, thin and transparent.
The dorsal margin straight in the right valve, broadly arched in
the left. The anterior end broadly and obliquely rounded, and
in the right valve bearing a few small marginal spines below
the middle. The posterior end obliquely subtruncate, the ven-

'Ulrich, E. O., and Bassler, R. S., Maryland Geol. Surv., Miocene
Report, 1904, pp. 94-130, pls. 35-38.





10 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

tral margin sinuous, the dorsal and ventral margins converging
posteriorly. Viewed from the inside, the valves are moderately
deep and are flanked by a faint, narrow, marginal area around
the anterior end, which is traversed by a few short radial pore
canals. Both valves bear a flange just anterior to the middle of
the ventral margin and the sharp, carinate border of the right
valve is removed from the outer margin a short distance
around the postero-ventral angle. The ventral margin of the
left valve is faintly grooved for the reception of the right.
The hinge of the right valve consists of a faint row of denti-
culations just anterior to the middle, behind which the dorsal
margin is grooved for a short distance and then it becomes
sharply prominent to the postero-dorsal angle. The hinge of
the left valve consists of a narrow, elongate, notched socket
anterior to the middle, behind which is a short, raised bar and
behiird that the dorsal margin is faintly grooved to the postero-
dorsal angle. The muscle scar pattern is relatively simple and
consists of four small scars in a vertical row in front of the
summit of which is a fifth.
Dimensions of Holotype No. 1032, a right valve: length,
0.90 mm.; height, 0.48 mm. Paratype No. 1033, a left valve:
length, 0.90; height, 0.50.
Both figured specimens are from Locality 41.
The species, while small and fragile, occurs abundantly at
most localities from the Chipola through the Arca zone of the
Choctawhatchee.

Cytheridea floridana Howe and Hough, n. sp.
Plate II, figures 15, 16, 18; Plate IV, figures 6, 10.
Carapace subovate, dorsal margin evenly arched, ventral
outline slightly down-curved; the anterior end broadly round-
ed, the posterior end subtruncate. The left valve larger and
overlapping the right around practically the entire periphery,
the greatest overlap being just anterior to the middle of the
dorsal margin. The ventral half of the anterior end of the
right valve carries several obscure, blunt spines. Viewed from
above, the anterior end keeled, the posterior end blunt. Sur-
face of the valves nearly smooth except for the widely spaced
normal pore canals. Greatest height just in front of the
middle, thickness nearly uniform from just in front of the
middle almost to the posterior end. Viewed from the inside,
the valves moderately deep, fringed around the anterior end




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 11

with a moderately broad marginal area which narrows con-
siderably around the ventral and posterior margins. The
margin of the right valve is acute and fits into a faint lipline
along the ventral and posterior margins of the left valve. The
marginal areas of both valves are crossed by numerous close-
ly spaced radial pore canals; in both valves the ventral mar-
gin is slightly flanged just anterior to the middle. The hinge
of the right valve consists of an elongate, notched cusp an-
terior to the middle, the cusp bearing twelve to fifteen small
denticulations. Immediately behind it, there is a small, deep
pit which has several faint denticulations on its lower side.
Behind this pit there is a narrow bar which, toward the poste-
rior end, becomes more and more prominent and breaks up
into a number of small teeth. The bar and teeth are separat-
ed from the dorsal margin by an incised line. The hinge of the
left valve consists of a deep, channeled, crenulate groove an-
terior to the middle, behind which is an elongate, smooth,
oblique protuberance, behind which the dorsal margin is
deeply grooved to the junction of the dorsal and posterior
margins, where a shallow, crenulate socket occurs. The muscle
scar pattern of this species is very complex and unlike that of
any other Cytheridea with which the writer is familiar. It is
very clearly marked on both specimens and is shown in de-
tail in Figure 18, Plate 2.
Dimensions of Holotype No. 1037, Locality 15: length, 1.03
mm.; height, 0.60 mm.; thickness, 0.50 mm.
This is the most abundant species in the Arca zone of the
Choctawhatchee; Localities 15, 40 and 41. Cytheridea sub-
ovata Ulrich and Bassler, which is very abundant in the Shoal
River Miocene of Florida, differs from it in being more elon-
gate and in having a more pointed posterior end.

Genus CYTHEROMORPHA Hirschmann
Cytheromorpha warneri Howe and Spurgeon, n. sp.
Plate II, figures 5, 8, 9; Plate IV, figure 4.
Carapace oblong ovate in outline, the males being more
elongate than the females. Dorsal and ventral margins are
nearly straight and converge gently toward the posterior, the
upper third of the anterior end is obliquely truncate, the re-
mainder regularly rounded; the upper two-thirds of the nar-
rower posterior end is obliquely truncate, the lower one-third





12 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

rounded so as to form an obscure angulation below the middle.
Greatest height at the anterior cardinal angle, thickness ap-
proximately equal throughout most of the length; surface
finely and regularly reticulate, the reticulations being roughly
hexagonal in outline and arranged in rows more or less par-
allel to the margins. There is a faint tendency to a median
sulcus. Viewed from the inside, the valves are moderately
shallow, shiny, translucent. The marginal area which is broad
around the anterior end, narrows considerably in the middle
of the ventral margin, widens again in the posterior half of the
ventral margin and becomes narrower around the posterior
end. The line of concrescence lies near the outer margin
around the anterior end, but elsewhere coincides with the
inner margin. The hinge of the right valve consists of a
small, button-shaped anterior tooth below the dorsal margin;
on either side of this tooth there is a small pit for the reception
of the two anterior teeth of the left valve. The dorsal margin
is nearly straight and grooved for the reception of a bar in the
opposite valve. The posterior cardinal angle is occupied by an
oval, oblique socket which has a bulbous swelling on either
side of it and a raised rim above it. The hinge of the left
valve consists of an anterior socket in front of which lies a
small, knob-like tooth and behind which lies the swollen an-
terior end of the hinge bar. The posterior cardinal angle is
occupied by a small, knob-like tooth with depressions in front
of and behind it. The tooth and depressions are flanked above
by the raised postero-dorsal margin. The pore canals are few
in number and regularly spaced around the anterior end.
Dimensions of Cotype No. 1070, a female: length, 0.58 mm.;
height, 0.30 mm.; thickness, 0.24 mm.
The figured specimens are all from the Choctawhatchee
Miocene, K. E. Young Locality 34, and are identical to numer-
ous specimens with which they have been compared from the
Calvert Miocene of Plum Point, Maryland.
This species is named in honor of Mr. A. D. Warner, Cin-
cinnati, Ohio.

Cytheromorpha warneri Howe and Spurgeon, var. okaloosaensis
Howe and Spurgeon, n. var.
This variety differs from the above described species in
that the anterior one-third to one-half of the carapace is
covered by fine, circular pits instead of angular reticulations.




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 13

There is also a pronounced median sulcus separating the two
types of ornamentation, which is most prominent near the
center of the valves and which curves backward as it ap-
proaches the dorsal margin.
Cotypes No. 1077 from the Upper Oak Grove Miocene, Lo-
cality 29. This variety occurs likewise abundantly in the Shoal
River Miocene, Locality 28, and in the Area zone of the Choc-
tawhatchee at Localities 15, 40 and 41. While these two va-
rieties appear to mark separate stratigraphic horizons in the
Florida Miocene, they occur together in the Calvert formation
of Plum Point, Maryland.

Genus CYTHERIDEIS Jones
Cytherideis agricola Howe and Hadley, n. sp.
Plate III, figures 27-30; Plate IV, figure 8.
Carapace elongate, inflated; dorsal margin go,--ly arched,
ventral margin nearly straight, central half slightly concave;
anterior end blunt and obliquely rounded; posterior end more
blunt and very obliquely rounded. Carapace nearly uniform
in height; greatest height being just in front of the center.
Viewed from above, the sides are nearly parallel except for
the pointed extremities. Exterior surface of the carapace dec-
orated with small pits arranged in curved lines nearly parallel
to the margins, tending to develop slight ridges on the an-
terior half; valves otherwise smooth. Marginal area widest at
anterior and posterior extremities; line of concrescence nearly
coincides with the inner margin except at the anterior, where
the inner lamella widens notably and slopes strongly away
from the median plane. The marginal area bears a raised rim
around the anterior, ventral and posterior portions. This rim
parallels the ventral margin near the outside, but on the poste-
rior it cuts straight and obliquely across the end, approaching
the inner margin; at the anterior end it comes nearer the inner
margin than it does the outer. This feature is more pronounced
in the left valve than in the right. Anterior half of the hinge
line of the right valve marked by a groove which opens into
the inner cavity anteriorly; posterior end marked by a small,
depressed socket, between the groove and the socket there pro-
jects a narrow, raised bar separated from the dorsal margin
by a narrow, incised line.
Dimensions of Cotype No. 1072: length, 0.90 mm.; height,
0.38 mm.; thickness, 0.36 mm.





14 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

The figured specimens are all from the Arca zone of the
Choctawhatchee at Locality 40. This species occurs also at
Locality 41.

Cytherideis ashermani Ulrich and Bassler.
Plate III, figures 8-10.
Cylherideis ashermani Ulrich and Bassler, Md. Geol. Surv., Mio. Rept.,
1904, p. 126, pl. 37, figs. 10-16.
Cytherideis longula Ulrich and Basslcr, Md. Geol. Surv., Mio. Rept.,
1904, p. 128, pl. 37, figs. 21-27.
Cytherideis semicircularis Ulrich and Bassler, Md. Geol. Surv., Mio.
Rept., 1904, p. 127, pl. 37, figs. 18-20.
Carapace elongate, subcylindrical, slightly curved with
broadest portion just posterior to middle. Ventral outline al-
most straight in left valve, slightly sinuate in right, dorsal
margin arcuate, ends rounded with posterior more acute than
anterior, particularly in right valve; surface strongly pitted
and slightly reticulate. Left valve slightly larger than right
and overlapping it except along posterior half of dorsal mar-
gin. Right valve, viewed from interior, moderately deep; mar-
ginal area narrow except around anterior end and flanged
from point anterior to dorsal margin around anterior, ventral
and posterior margins; the flange being distinctly removed
from outer margin along anterior end and around acute basal
tip of posterior end. This flange fits into a lipline which par-
allels the outer margin of the left valve. The hinge of the right
valve consists of an elongate narrow groove on the enrolled
dorsal margin and extends from a point just anterior to the
middle to the posterior cardinal angle and is terminated at
both ends by the projection of the flange previously mentioned.
The hinge of the left valve consists of an elongate groove or
socket open to the anterior and situated below the dorsal mar-
gin just anterior to the middle. A similar, but much smaller,
socket is situated at the posterior cardinal end. Between these
sockets the dorsal margin is flattened and projecting and fits
into the groove of the right valve. The line of concrescence
coincides with the inner margin except for short distance
around the anterior end, where it lies just inside of it. Normal
pore canals are inconspicuous; radial pore canals not well
enough preserved to establish pattern, but in several speci-
mens appear to be numerous and grouped in bunches about
anterior end.
Dimensions of Plesiotype No. 1051, bivalved specimen:
length, 0.90 mm.; thickness, 0.40 mm.; Plesiotype No. 1050, right





CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 15

valve: length, 1 mm.; height, 0.41 mm.; Plesiotype No. 1049,
left valve: length, 0.96 mm.; height, 0.46 mm.
The figured specimens are all from the Area zone of the
Choctawhatchee at Locality 40. The Area zone specimens are
larger and somewhat more coarsely pitted than the specimens
found at Plum Point, Maryland, the type locality, but the differ-
ences are too slight to be worthy of even varietal mention.

Cytherideis fabula Howe and Dohmn, n. sp.
Plate III, figures 15, 16, 20, 23; Plate IV, figure 2.
Carapace elongate, convex, the ventral outline slightly con-
cave, the dorsal outline nearly semicircular. Greatest thickness
of the carapace just behind and a little below the middle. The
ends obliquely rounded, the anterior end much broader than
the posterior. Greatest length near the ventral margin. Surface
smooth. The left valve larger than the right and overlapping it
along the dorsal margin and along the middle of the ventral
margin. The interior of the valves moderately deep, some-
what irregular with the normal pore canals showing as larger
pits on the interior than on the exterior. The marginal area
of each valve bears a thin, raised line just within the outer
margin. The marginal areas are broad around the anterior
end and fairly broad near the acute posterior extremity. The
line of concrescence lies near the outer margin around the
central portion of the two extremities. The radial pore canals
are clearly marked under transmitted light; the anterior and
posterior ends carrying about fifteen each, occurring, for the
most part, on the ventral half and somewhat irregularly spaced,
the ventral side carrying about twenty-one or twenty-two, also
irregularly spaced. Hingement simple; the hinge of the left
valve consisting of an elongate, projecting bar lying back of the
middle and not separated from the dorsal margin. Anterior to
the bar there is a deep, slightly arcuate groove. Below the
dorsal margin and posterior to the bar, there is a shorter, nar-
rower groove, the posterior end of which is open to the interior
of the valve. In the right valve, the posterior half of the dorsal
margin carries a narrow groove into which the projecting bar-
like extension of the opposite valve is received.
Dimensions of Cotype No. 1056: length, 0.88 mm.; height,
0.38 mm.; thickness, 0.39 mm.
The figured specimens are all from Locality 40.
The species is also abundant at Localities 15 and 41.





16 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

Cytherideis ulrichi Howe and Johnson, n. sp.
Plate III, figures 11-14.
Carapace elongate, inflated particularly toward the poste-
rior end. The dorsal margin gently arched, the ventral margin
nearly straight, slightly concave just in front of the middle.
The anterior and posterior ends obliquely rounded, subequal
in the right valve, the posterior slightly larger in the left. Sur-
face of the carapace smooth, but marked with fairly numerous
white spots where the normal pore canals approach the sur-
face. Viewed from the inside, the valves are moderately deep,
flanked by a well defined marginal area, which is broadest
around the anterior end, where, for a short distance, the line
of concrescence leaves the inner margin and approaches the
outer. Radial pore canals moderately numerous and occurring
in bunches of two or three around the anterior end, fewer in
number along the ventral and posterior margins. The mar-
ginal area of right valve bears a low, sharp flange except for
a short distance along the hingeline, where the dorsal margin
is grooved. This groove starts at the middle and extends about
one-third the distance to the posterior extremity. The mar-
ginal area of the left valve bears a faint lipline near the out-
side and the hinge consists of a sharp infolding of the dorsal
margin from the center one-third the distance to the posterior
extremity. Behind and below this fold is a short, horizontal
gash, in front of it and below the dorsal margin is an elongate,
shallow socket.
Dimensions of Cotype No. 1052, a right valve: length, 1.03
mm.; height, 0.47 mm.; Cotype No. 1053, a left valve: length,
1.04 mm.; height, 0.47 mnm.
Both figured specimens came from Locality 40. It occurs
also at Locality 15.
The species is named for Dr. E. O. Ulrich, who has con-
tributed so much to our knowledge of American Ostracoda.

Genus CYTHERIDELLA Daday.
Cytheridella chambers Howe, n. sp.
Plate III, figures.1-2; Plate IV, figures 16, 20.
Carapace in side view ovate, the. dorsal and ventral mar-
gins nearly straight and converging strongly toward the poste-
rior. Posterior obliquely(truncate above, rounded below and
subangular near the middle. The anterior end broadly rounded





CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 17

and bearing a few flattened tubercules along the lower half of
the margin. The junction of the ends with the dorsal margin
forms mild angulations. Surface of the carapace swollen,
finely reticulate over the central portion and bearing a sub-
central node at the position of the muscle scars behind which
is a broad, semicircular, shallow sulcus. The eye spots are
well marked and there are two small spines, one near the
dorsal margin about one-third of the distance from the poste-
rior cardinal to the anterior cardinal angle, the other below
and slightly in front of it on the inflated portion. These two
spines are more pronounced in the right valve than in the left
and .are not present on all specimens. Viewed from the in-
side, the valves are moderately deep, irregular and sufficiently
transparent so that the reticulate pattern shows through from
the outside. The marginal area is very narrow throughout
and bears only a small number of radial pore canals. The
ventral margins of both valves are flanged, that of the right
valve at about the middle; that of the left valve, slightly be-
hind the middle. The flange of the left valve tends to be bifid.
The hinge of the right valve consists of two, low, elongate
teeth which reach their greatest height toward the extremities.
The dorsal margin is straight between them and carries a very
faint, narrow groove, which is minutely crenulate. The hinge
of the left valve is wholly toothless. The straight, sharp edge
of the dorsal margin fits into the fine groove of the opposite
valve and the margin at anterior and posterior cardinal angles
is gently arched to fit over the teeth of the opposite valve. The
muscle scar pattern consists of four, oval muscle scars in a
vertical row, in front of and below which is a second row of
four muscle scars which are spaced at unequal distances.
Dimensions of Holotype No. 1043, a right valve, from Lo-
cality 41: length, 0.66 mm.; height, 0.38 mm.; and Paratype No.
1044, a left valve, from Locality 41.: length, 0.68 mm.; height,
0.39 mm.
Named in honor of Mr. Jack Chambers, Paleontologist,
United Gas Company, Houston, Texas, who helped in the pre-
liminary study of this fauna.
The species also occurs at Locality 40. This species belongs
to a genus which has a large number of representatives in the
Miocene of the Gulf and Atlantic coasts. It is closely related to
Cythere dorsicornis Ulrich and Bassler, var. bicornis Ulrich





18 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

and Bassler, described from the Choptank Miocene of Pawpaw
Point, Maryland, which variety, however, differs in having
reticulations over the entire carapace.

Genus CYTHEREIS Jones
Cythereis exanthemata (Ulrich and Bassler), var. marylandica Howe
and Hough, n. var.
Plate I, figures 1-5; Plate IV, figure 7.
Carapace oblong, subquadrate, obliquely rounded at the
ends, the greater curvature being below the middle of the an-
terior end and at the middle of the posterior end. The anterior
end is fringed with numerous small, flattened spines, bordered
by a marginal ridge which starts at the ocular spot just below
the dorsal margin and continues almost to the middle, where
it breaks up into a second row of broad, flattened spines. The
posterior end is fringed by a double row of spiny tubercles,
and the ventral margin carries a few obscure, spiny protuber-
ances. The central portion of the valve is decorated with three
distinct, longitudinal rows of vertically elongated spines. One
of these rows parallels the dorsal margin and the spines pro-
ject over it. The second row starts at the central bump formed
by the muscle scar attachment and continues obliquely across
the central portion of the carapace to a point below and in
front of the posterior cardinal angle, where a vertical row of
three of four nodes connects with the dorsal row. The third
row is situated just above the ventral margin and parallels the
second row. Viewed from the inside, the valves are moderately
shallow and the depressed portion is bordered by a wide, dis-
tinct marginal area around the anterior, ventral and posterior.
This marginal area is crossed by numerous paired radial pore
canals which terminate in the flattened spines on the eiids.
The marginal areas of both valves have two, parallel "lip-
lines" or faintly incised grooves, and both are infolded slightly
just anterior to the middle of the ventral side. The hinge of
the right valve consists of a prominent anterior tooth, in front
of which is a deep depression leading to the eyespott." Be-
hind and beneath the tooth is an oblique socket, which con-
tinues as a narrowing, shallow furrow below the dorsal mar-
gin to the posterior cardinal angle, where is situated a rounded,
backwardly curved tooth. The hinge of the left valve consists
of a large, deep socket at the anterior, separated from the
eyespott" depression by a thin, oblique septum. Behind the





CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 19

socket is a small, blunt knob, the upper edge of which connects
with a high, straight bar leading to the posterior cardinal
angle. The bar is separated from the dorsal margin by an in-
cised line. The posterior cardinal angle is marked by a large,
deep socket open to the interior. Muscle scars consist of four
oval spots in a vertical row, in front of the middle of which is
a fifth, and below it a sixth.
Dimensions of Cotype No. 896: length, 0.93 mm.; height,
0.56 mm.; thickness, 0.52 mm.
All figured specimens are from the Calvert formation Mi-
ocene of Plum Point, Maryland. The variety occurs rarely in
the Arca zone of the Choctawhatchee at Localities 15, 40 and
41. It is somewhat commoner in the Upper Choctawhatchee
at Locality 14 and K. E. Young Locality 34. It is much higher
and more coarsely ornamented than the typical form which
was described from the Calvert formation of Maryland.

Cythereis exanthemata (Ulrich and Bassler), var. gomillionensis Howe
and Ellis, n. var.
Plate I, figures 6-12; Plate IV, figure 3.
Variety differing from the preceding in its much smaller
size, more elongate form, more delicate ornamentation and in
the greater number of nodes which decorate the central portion
of the carapace. In particular there are usually three addi-
tional nodes in front of the central row of spines placed ap-
proximately equidistant between the muscular tubercle and
the anterior rim. In addition this variety possesses a supple-
mentary row of very fine, globular nodes situated above the
dorsal row of spines along the hingle-line of the right valve.
In most specimens this line of nodes extends the entire dis-
tance from the anterior cardinal angle to the posterior cardinal
angle, but in some specimens is found only on the anterior
half of the hinge-line. This supplementary row of nodes easily
separates this variety from either the preceding variety or
from the typical species.
Dimensions of Cotype No. 888, a complete female speci-
men: length, 0.79 nmm.; height, 0.43 mm.; thickness, 0.43 mm.;
and Cotype No. 899, a male left valve: length, 0.73 mm.; height,
0.39 mm.
All figured specimens came from the Arca zone of the
Choctawhatchee Miocene, Locality 41. The variety occurs
commonly also at Localities 15 and 40.





20 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

Cythereis garretti Howe and McGuirt, n. sp.
Plate III, figures 17-19; Plate IV, figures 5, 15.
Carapace ovate, the dorsal and ventral margins nearly
parallel so that the height varies but little between the anterior
and posterior cardinal angles; greatest thickness just posterior
to the middle and being equal to somewhat more than one-
half the length. The surface is irregularly papillate except in
the anterior and posterior margins. The dorsal margin is near-
ly straight, the ventral margin inwardly flexed toward the
middle, the anterior and posterior ends broadly rounded and
bordered by a moderately broad marginal area, which is
crossed by numerous fine, nearly straight radial pore canals.
The inner margin and line of concrescence coincide through-
out. The marginal area of the right valve bears four, well-
defined lip-lines. The outermost two of these grooves start
above the anterior hinge tooth and parallel the outer margin
to the posterior side of the posterior hinge tooth. They are
flanked on the inside by a moderately high flange, inside of
which are two faintly incised lines. The outer margin of the
left valve is acute and is only faintly marked by lip-lines. The
hinge of the right valve consists of a high, strong anterior
tooth, situated immediately above a small, circular, ocular pit
and behind which is a deep, subcircular socket. Extending
from this socket to the posterior cardinal angle is a well
defined groove below a narrow, sharp bar, which is separated
from the dorsal margin by a faintly incised line. The posterior
tooth is large, blunt, slightly curved and is elongated parallel
to the postero-dorsal slope. The hinge of the left valve is more
delicate and consists of a large, anterior socket above and
separated from a small, ocular pit by a thick, low septum.
Behind the socket is a nearly circular tooth, from the poste-
rior side of which extends a long, straight bar to a broad,
oval, shallow, posterior socket. The bar is separated from the
dorsal margin by a deeply incised groove and it continues as a
semicircular rim around the outside of the posterior socket.
The muscle scar pattern consists of four small spots in a ver-
tical row, with two in front and two near the ventral margin.
Dimensions of Cotype No. 1058, a right valve from the Arca
zone, Locality 41: length, 0.96 mm.; height, 0.61 mm.; and
Cotype No. 1057, a left valve from the Arca zone, Locality 40:
length, 0.92 mm.; height, 0.61 mnm.




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 21

The species is based on these two specimens, which were
the only ones found in the samples from the Arca zone. There
is a somewhat similar species which occurs rarely in the
Ecphora zone of the Choctawhatchee, at Jackson Bluff, Leon
County, Florida. The Ecphora specimens, however, are much
less ornate. The species is related to Cythere clarkana Ulrich
and Bassler from the Calvert formation of Maryland, but that
species is more elongate and the ventral side of it is distinctly
flattened.
Named in honor of Julius B. Garrett, Jr., Chief Paleontolo-
gist, Stanolind Oil and Gas Co., Houston, Texas.

Cythereis gunteri Howe and Chambers, n. sp.
Plate I, figures 13-17; Plate IV, figure 1.
Carapace small, subovate; highest at the anterior cardinal
angle, thickest at the small node just anterior to the middle.
Dorsal outline straight except for slight projections at the
cardinal angles. Ventral outline slightly sinuous. Anterior
end broadly and obliquely rounded, slightly produced ven-
trally with a faintly raised rim, below which are eight or more
small tubercles situated below the middle. Posterior end nar-
rower, yet broadly rounded and slightly produced dorsally.
The surface of the valves is ornamented with a number of
raised lines which radiate irregularly from a small node just
anterior to the middle. Surface of the valves smooth, sparsely
punctate. The hinge of the right valve consists of a high,
sharp anterior tooth, behind which is a small, nearly circular
socket, which continues as a narrow groove below the sharp
edge of the dorsal margin to the posterior cardinal angle,
where a high, blunt tooth is situated oblique to the dorsal
margin. The ventral margin has a small, inordinately curving
flange just in front of the middle. The hinge of the left valve
has a deep, nearly circular anterior socket, which is flanked
in front by a knob-like projection of the dorsal margin, be-
hind by a dorsally curved, sharp, almost tooth-like plate. At
the posterior end of the hingeline there is a deep, oblique
socket and between the anterior and posterior hingements, the
dorsal margin is straight and sharp without any noticeable
sign of a groove. The posterior, ventral and anterior mar-
gins are doubly grooved by two faint incised lines and the ven-
tral margin is thickened and slightly flanged near the middle.
The line of concrescence corresponds to the inner margin ex-





22 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

cept for a very short distance around the anterior end. The
marginal area is broad and traversed by numerous thread-
like radial pore canals, the pore canals being grouped in
bunches of two, three and four.
Dimensions of Cotype No. 1000: length, 0.85 mm.; height,
0.48 nmm.; thickness, 0.37 nmm.; Cotype No. 1009: length, 0.86
nun.; height, 0.50 nmn.; and Cotype No. 1010: length, 0.83 nmm.;
height, 0.43 nmm.
Named in honor of Herman Gunter, for many years State
Geologist of Florida.
This species is closely related to Cythere martini Ulrich
and Bassler, described from the Choptank and Calvert forma-
tions of Maryland. It differs from it in having much fewer and
coarser ribs over the central portion of the carapace. In
Cythere martini, the ornamentation consists of a reticulate
network formed by small transverse bars between the radial
ribs.
The figured specimens are described from the Arca zone of
the Choctawhatchee Miocene, Locality 41. It occurs also at
Localities 15 and 40, but has not been observed elsewhere.

Cythereis product (Ulrich and Bassler).
Plate I, figures 31, 32, 35-37; Plate IV, figures 11, 12.
Cythere product Ulrich and Bassler, Md. Geol. Surv., Mio. Rept., 1904,
p. 115, pl. 36, fig. 17; pl. 38, figs. 28-30.
Carapace in side view elongate ovate, dorsal and ventral
margins slightly sinuous and nearly parallel, the anterior end
broadly and obliquely rounded and forming a distinct and
prominent angulation with the dorsal margin, produced ven-
trally, faintly rimmed and decorated with eight to ten small,
marginal teeth below the middle. The posterior end rounded,
but tending to a slight angularity just above the middle. It,
too, tends to be faintly denticulate. The remainder of the
surface is reticulate with a tendency for the reticulations to be
elongated longitudinally. There is a low swelling marking the
position of the muscle attachment just anterior to the middle
and the eyespots are small, circular and very clearly defined.
Greatest height at the anterior cardinal angle; greatest thick-
ness near the posterior end, but it is only slightly more than
the thickness near the anterior end. Viewed from the inside,
the valves are moderately shallow, particularly at the anterior
ends and fringed with a fairly wide marginal area. The line




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 23

of concrescence lies between the inner and outer margins,
around the anterior end and around the central portion of the
posterior end. The marginal area of the right valve bears a
broad, shallow lip-line near the outer margin, into which the
acute outer margin of the left valve fits. The ventral margins
of both valves are incurved and flanged just anterior to' the
center, the flange of the left valve being bifid. The hinge of the
right valve consists of a high, sharp anterior tooth, whose
base curves posteriorly downward below a deep anterior socket
which is situated, immediately above and behind, a small cir-
cular, ocular pit. The inner edge of the dorsal margin appears
to be faintly grooved and the posterior cardinal angle is oc-
cupied by a large, oval, mushroom-shaped tooth. The hinge of
the left valve consists of a deep, circular, anterior socket, situ-
ated above and behind a small, circular, ocular pit and separ-
ated from it by a low, thick septum. The dorsal margin projects
in a tooth-like manner immediately in front and behind the
socket, otherwise it is straight, narrow and sharp to the poste-
rior angle, where is situated an ovate pit, partially open to
the interior. The radial pore canals are numerous; normal
pore canals are few and widely spaced and mostly obscured
by the reticulate ornamentation.
Dimensions of Plesiotype No. 1023: length, 0.90 mm.;
height, 0.42 mm.; thickness, 0.37 mm.
The figured specimens are all from Locality 41 at Red Bay,
Florida. The species occurs also at Localities 15 and 40. The
Florida Miocene specimens have been compared with numer-
ous specimens from the Calvert formation of Plum Point,
Maryland, the type locality, and are apparently identical in
every particular. So far, the species has been found only in
the Arca zone of the Choctawhatchee Miocene of Florida.

Cythereis rugipunctata (Ulrich and Bassler).
Plate I, figures 18, 20-22; Plate IV, figures 22, 23.
Cythere rugiplincataa Ulrich and Bassler, Md. Geol. Surv., Mio. Rept.,
1904, p. 118, pl. 38, figs. 16, 17.
Carapace in side view elongate ovate; highest at the an-
terior cardinal angle; thickest at the muscular protuberance.
Anterior end broadly and obliquely rounded with a distinct
rim and with four or five small marginal spines in the ventral
half; posterior end concave in the dorsal half, convex and or-
namented with three or four prominent spines in the ventral




24 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

half. Dorsal margin nearly straight, ventral margin sinuous,
with two margins tending to converge posteriorly. Ornamenta-
tion of the central portion of the carapace consisting of a prom-
inent node just anterior to the center, behind and below which
is a curved sulcus. The surface of the posterior half of the cara-
pace is a complex of oblique plications which tend to produce a
divaricate effect along the median line of the valves. Anterior
to the central node, the plications are irregularly distributed.
There is a small, ocular spot just below the anterior cardinal
angle. Viewed from the inside, the valves are moderately deep
and are bordered with a wide marginal zone, widest along the
posterior half of the ventral margin. The marginal area of the
right valve possesses a well marked "lip-line" just inside fhe
outer margin, into which the acute outer margin of the left
valve articulates. The radial pore canals are moderately few
in number, being most abundant around the anterior end. The
hingement of the right valve is elongate and consists of a small,
high anterior tooth, behind which is a deep socket, tending
to be open to the interior. From this socket a narrow, straight
groove parallels the dorsal margin to the oblique, blunt, re-
curved posterior tooth. There is also a second groove below
the first, which starts at the anterior socket and continues back
about one-fifth the distance to the posterior cardinal angle.
The hinge of the left valve consists of a small anterior socket,
behind which is a moderately high tooth, followed by a straight
bar parallel to and separated from the dorsal margin by a faint
incised line. This bar terminates at its posterior end in a small
swelling and is in turn followed by a wide, oblique socket,
which is open to the interior of the valve.
Dimensions of Plesiotype No. 1011: length, 0.65 mm.; height,
0.38 mm.; thickness, 0.36 mm.
The figured specimens are all from the Arca zone of the
Choctawhatchee Locality 40, where the species is quite com-
mon. It occurs also at Localities 15 and 41 and is increasingly
more abundant in Miocene and Pliocene localities younger
than the Arca zone. The writer's collections do not, however,
show it to be present in beds older than the Arca zone, though
there is a closely related but much smaller species in the Byram
marl (Oligocene of Mississippi).




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 25

Cythereis vaughani (Ulrich and Bassler).
Plate III, figures 24-26; Plate IV, figure 13.
Cythere vauighani Ulrich anl Bassler, Md. Geol. Surv., Mio. Rept., 1904,
p. 109, pl. 38, figs. 25-27.
Carapace elongate with an obliquely rounded anterior end
and a posterior end that is rounded below the middle and con-
cave above. The dorsal margin is nearly straight, the ventral
subparallel to it and slightly sinuous. The anterior, ventral
and lower half of the posterior margins are finely and evenly
denticulate, particularly in the right valve. Viewed from the
outside, the anterior end carries a thin marginal rim. Sur-
face with three or four longitudinal ridges and an irregular
number of transverse raised bars, forming an angularly retic-
ulate pattern which is somewhat variable. In addition to the
pattern of ridges, the valves bear a small, round, almost glassy
knob just in front of the center and a somewhat similar glassy
tubercle at the eyespott" just below the anterior cardinal
angle. Viewed from the interior, the valves are moderately
deep and are fringed with a fairly broad marginal area, which,
in the right valve, carries a deeply grooved lip-line near the
outer margin to receive the rather acute marginal edge of the
opposite valve. Radial pore canals are numerous and closely
spaced around the anterior end, becoming fewer and wider
spaced along the ventral and posterior margins. The hinge of
the right valve consists of a small, knob-like anterior tooth, in
front and below which lies a small, ocular pit and behind
which is a large, shallow depression open to the interior. This
pit is situated below a long, straight, narrow, oblique hinge bar,
which terminates at the posterior cardinal angle above a small,
round, knob-like tooth which is situated on the posterior mar-
gin. The hinge of the left valve consists of a small anterior
socket, situated above and behind a deep ocular pit and sep-
arated from it by a low rim, and with two tooth-like projec-
tions, one just in front, formed by an overlap of the dorsal
margin, the other immediately behind and below the dorsal
margin. The dorsal margin is nearly straight and oblique
and faintly grooved. The posterior cardinal angle is occupied
by a large, shallow socket, which is elongated parallel to the
posterior slope.
Dimensions of Plesiotype No. 1073: length, 0.73 mm.;
height, 0.38 mm.; thickness, 0.30 mm.
The figured specimens are all from the Choctawhatchee
Miocene, K. E. Young Locality .34, The species occurs rarely

0'.





26 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

in the Area zone, Locality 41. It occurs with increasing abund-
ance in Miocene localities younger than the Arca zone of the
Choctawhatchee, and is one of the commonest ostracodes in
the Caloosahatchee Pliocene of Florida, and an almost identical
form is living off the coast of Haiti. It has not so far been ob-
served in deposits older than the Area zone.

Cythereis (Pterygocythereis) cornuta, var. americana Ulrich and
Bassler.
Plate II, figures 19, 21-24; Plate IV, figure 24.
Cythereis cornuta var. americana Ulrich and Bassler, Md. Geol. Surv.,
Mio. Rept., 1904, p. 122, pl. 37, figs. 29-33.
This species was described from the Calvert formation at
Plum Point on Chesapeake Bay, Maryland. The writer has
had numerous specimens from the type locality for comparison
and is convinced that the common Pterygocythereis of the
Florida Middle Miocene should be considered as no more than
a variant of the Maryland species. The present author will
describe some of the details of the carapace, not mentioned in
the original description, as an aid in recognition.
The hinge of the right valve is rather delicate and consists
of a moderately small, knob-like tooth on the anterior end,
behind which is a small, circular depression which continues
as a narrow groove below and parallel to the dorsal margin
to the anterior cardinal angle, where is located a low, oval,
blunt tooth. The hinge of the left valve is slightly more robust
and consists of an anterior socket open below, behind which is
a small, sharp tooth situated immediately below the dorsal
margin. The dorsal margin is thin and sharp and fits into the
groove of the opposite valve. The posterior cardinal angle is
occupied by an elongate socket open in the interior. The mar-
ginal areas are moderately broad on the anterior and posterior
ends and carry a few widely spaced radial pore canals. These
pore canals tend to be grouped in pairs, particularly on the
anterior end. The species ranges from the Chipola to the
Upper Choctawhatchee; Localities 10, 15, 28, 40, 41 and K. E.
Young Locality 34.
Dimensions of Plesiotype No. 1039, from Shoal River Mi-
ocene, one mile west of Valley Church, Walton County,
Florida; length, 0.95 mm.; height, 0.44 mm.; thickness, 0.63



c -, a a




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 27

Genus HEMICYTHERE Sars
Hemicythere conradi Howe and McGuirt, n. sp.
Plate III, figures 31-34; Plate IV, figure 17.
Carapace small; thickest near the middle, greatest thick-
ness being slightly less than one-half the length; highest at the
anterior cardinal angle; in side view subovate. Dorsal margin
faintly arched, ventral margin with a slight concavity near the
middle; both margins converging posteriorly. Anterior end
broadly rounded, dorsal portion oblique; posterior end narrow,
compressed and with distinct angles where it meets the dorsal
and ventral margins; both anterior and posterior ends possess
a low, rounded rim. Surface of the valves reticulate, the reti-
culations being somewhat linear in arrangement. Interior of
the valves deep, nearly smooth. The inner margin projects
around the anterior, ventral and posterior ends, and the line
of concrescence lies nearer the outer margin on the anterior
end, and nearer the inner margin on the posterior end. The
marginal area of the left valve possesses a faint groove into
which is fitted a low, sharp ridge in the marginal area of the
right valve. The ventral margins of both valves are slightly
flanged just anterior to the middle. The hinge of the right
valve consists of a large, high, knob-like tooth on the anterior
end, behind which is a large, broad pit, followed by a narrow
groove which parallels the dorsal margin and is terminated at
a large, oval, oblique, projecting tooth at the posterior cardinal
angle. The hinge of the left valve consists of a deep, nearly
circular socket, behind which is a low, broad, blunt tooth, the
upper edge of which joins a low, sharp bar, which parallels the
dorsal margin and which is separated from the dorsal margin
by a broad, depressed area. The posterior end of the hinge is
occupied by a large, shallow, oval socket. The muscle scar
pattern is situated somewhat anterior to the middle of the
carapace and consists of eleven, irregular, small, lucid spots.
The muscle scar pattern is taken from Paratype No. 1076, a
specimen found in the Cancellaria zone of the Choctawhatchee
Miocene at Jackson Bluff, Locality 14.
Dimensions of Cotype No. 1066, a complete specimen, Lo-
cality 41: length, 0.60 mm.; height, 0.38 mm.; thickness, 0.26
nim.; Cotype No. 1068, a right valve: length, 0.58 mm.; height,
0.34 mm.; and Cotype No. 1067, a left valve, Locality 40: length,
0.60 mm.; height, 0.40 mm.





28 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

Named in honor of Timothy Conrad, the pioneer paleontol-
ogist of the Gulf Coast.
This species has a range in our collections from the Chipola
formation to the top of the Choctawhatchee.

Hemicythere dalli Howe and Brown, n. sp.
Plate II, figures 1-3; Plate IV, figure 18.
Carapace small, elongate, thickest in front of the middle,
highest toward the anterior. Dorsal margin nearly straight;
anterior cardinal angle has a small, glassy tubercle just below
it in each valve. Anterior end broadly rounded and rather
strongly produced ventrally. Ventral margin concave inward,
the point of greatest concavity lying in front of the middle.
Dorsal half of the posterior margin obliquely truncated, ven-
tral half more rounded. Surface marked with very faint rib"
the most pronounced running parallel to and near the posterior
margin. Behind this rib the thickness decreases sharply. The
remaining ribs, six or seven in number, when present, are very
faint and tend to run longitudinally, though curving near the
anterior end. The inner surface of the valves finely granular
in appearance except in the marginal areas which are crossed
by numerous straight, nearly evenly spaced, radial pore canals.
The hinge of the right valve consists of a small, knob-like an-
terior tooth, behind which is a deep, oval, oblique socket from
which extends a narrow groove, parallel to and just below the
dorsal margin, which is faintly arched. The posterior end of
the hingement consists of a large, blunt tooth, elongated paral-
lel to the postero-dorsal slope. There is a small, sharp, in-
wardly curved flange near the center of the ventral margin.
Immediately below this flange there is a shallow groove which
continues along the center of the margin to the posterior end.
The hinge of the left valve consists of a deep, anterior socket,
behind which is a nearly circular, pointed tooth. A straight,
narrow bar extends from the upper edge of this tooth to a large
posterior socket; the bar is separated from the dorsal margin
by a narrow, incised line.
Dimensions of Cotype No. 1026: length, 0.65 mm.; height,
0.34 mm.; and Cotype No. 1027: length, 0.67 mm.; height, 0.33
mm.
Named in honor of Dr. William Healey Dall, who will be
forever remembered for his monumental work on Tertiary
faunas of Florida.





CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 29

This species is abundant in the upper Oak Grove sand, Lo-
cality 29. The species shows considerable variation in the
matter of ornamentation, ranging from specimens which have
a completely smooth surface to ones in which the low ribs,
above described, are clearly discernable. In the Arca zone of
the Choctawhatchee, a single complete specimen was found in
which the ribs were so pronounced that the authors felt it
advisable to give it a tentative varietal name.

Hemicythere dalli Howe and Brown, var. redbayensis Howe and Brown,
n. var.
Plate II, figures 4, 7.
This variety differs from the typical form in being much
lower posteriorly and in having much more pronounced orna-
mentation. It possesses much of the same pattern of longi-
tudinal ribs as Cythere punctistriata Ulrich and Bassler of the
Maryland Miocene, but that species has a definite reticulate
pattern of cross riblets between the main ribs, and the left
valve is considerably more pointed posteriorly. It is based on
a single complete specimen, Holotype No. 1028, found in the
Arca zone of the Choctawhatchee, Locality 40.
Dimensions of Holotype No. 1028: length, 0.54 mm.; height,
0.30 mm.; thickness, 0.21 mm.

Hemicythere sellardsi Howe and Neill, n. sp.
Plate II, figures 6, 10.
Carapace small, compressed, subtriangular in outline, the
dorsal and ventral margins sinuous and converging toward
the posterior. The anterior end broadly rounded, the posterior
end much narrower and distinctly angled where it meets the
dorsal and ventral margins. The ornamentation consists of a
prominent, raised rim, which starts at the anterior cardinal
angle, follows for some distance the anterior and ventral mar-
gins, then turns sharply upward. to the posterior cardinal
angle, where it tends to form a knob. From this knob, a low
rim parallels the dorsal margin about one-half the distance
back toward the anterior cardinal angle. There are a number
of short, transverse, raised ribs on either side of this rim
which produce subreticulate effects about the borders. Central
portion of the carapace is nearly smooth.
Dimensions of Holotype No. 1031: length, 0.59 mm.; height,
0.32 mm.; thickness, 0.20 mm.





30 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

Named in honor of E. H. Sellards, formerly State Geolo-
gist of Florida.
The species is based on a single complete carapace found
in the Choctawhatchee Miocene, Locality 40. The author felt
that its appearance was so unique that, even though based on
a single specimen, it was worthy of a specific name.

Genus BASSLERELLA Howe, n. gen.
Genotype Basslerella miocenica Howe.
Carapace elongate, ovate, nearly twice as long as high;
thickest and highest posterior to the middle; the dorsal and
ventral margins subparallel; the anterior end regularly
rounded; the posterior end rounded below, subtruncate above,
forming almost a right angle with the dorsal margin; surface
smooth; the left valve considerably larger than the right and
overlapping it, the greatest overlap being at the postero-dorsal
angle and along the middle of the ventral margin. Viewed
from above, the carapace is bluntly wedge-shaped, the sides
sloping from near the posterior end toward the anterior, which
is narrowly rounded. Viewed from the inside, the valves are
moderately shallow and smooth. The marginal area is mod-
erately broad and the line of concrescence lies between the
inner and outer margins around the anterior end. The radial
pore canals around the_ anterior end are comparatively few
in number and are bent upward in the upper half and down-
ward in the lower half. They are few in number along the
ventral and posterior margins. The hinge of the right valve
consists of a strong, high, sharp, anterior tooth, which lies nim-
mediately below a faint depression of the antero-dorsal slope.
Immediately behind it lies a deep, oblique socket, behind
which there extends a narrow groove below and parallel to
the dorsal margin, the groove becoming deeper as the poste-
rior is approached. The posterior cardinal angle is occupied
by a high, dorsally recurved, oblique, mushroom-shaped tooth.
This tooth projects above and back from the dorsal margh
and is responsible for the pronounced angulation at the poste-
rior socket of the opposite valve. The hinge of the left valve
consists of a deep anterior socket, which is open to the in-
terior in front. It is flanked behind by a narrow, high, pointed,
almost blade-like tooth, which is distinctly separated from fhe
dorsal margin by a well defined groove. This groove, or in-





CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 31

cised line, extends along the edge of the dorsal margin all
the way from the anterior socket to the posterior socket. Be-
low the groove lies a heavy, thick bar, the anterior end of
which is downward and outwardly curved to form the pre-
viously mentioned blade-like tooth. The posterior cardinal
angle is occupied by a deep, oval, oblique socket, flanked on
either side by slight swellings of the margin.
To this genus the writer assigns the specimens figured by
Muller4 as Cythereis teres Brady. The Florida Miocene speci-
mens, while common, do not show the muscle scars well.
Muller's figure shows four oval scars in a verticle row near the
center, a short distance in the front of the middle of which is
a small, heart-shaped spot.

Basslerella miocenica Howe, n. sp.
Plate I, figures 19, 24-26.
Carapace elongate, ovate, bean-shaped, smooth; thickest
and highest posterior to the middle. Dorsal and ventral mar-
gins slightly arched and subparallel, the anterior end regularly
rounded and the posterior end rounded below, subtruncate
above, forming almost a right angle with the dorsal margin.
The left valve is considerably larger than the right and over-
laps it; the greatest overlap being at the posterior cardinal
angle and along the middle of the ventral margin. Viewed
from above, the carapace is bluntly wedge-shaped, the sides
sloping from near the posterior end toward the anterior, which
is narrowly rounded. Viewed from the inside, the valves arc
moderately shallow and smooth, flanked by a broad marginal
area around the anterior end and a much narrower marginal
zone along the ventral and posterior sides. The line of con-
crescence coincides with the inner margin except around the
central portion of the anterior end, where it comes close to the
outer margin. The radial pore canals are only moderately
common around the anterior end and tend to be inclined
away from the center of the anterior.. They are fewer in num-
her along the ventral and posterior margins. The margin of
the right valve carries a sharp lip near the outside, which is
slightly incurved near the middle of the ventral margin. It
fits into a faintly incised lip-line in the left valve. The hinge
of the right valve consists of a strong, high, sharp antei'ior

'Muller, G. W., "Fauna and Flora des Golfes von Neapel," Berlin,
1894, p. 379, pl. 29, figs. 6, 15; pl. 31, figs. 35-39.





32 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

tooth, which lies immediately below a faint depression of the
antero-dorsal slope. Immediately behind it lies a deep, oblique
socket, behind which there extends a narrow groove below
and parallel to the dorsal margin, the groove becoming
deeper as the posterior is approached. The posterior cardinal
angle is occupied by a high, dorsally recurved, oblique, mush-
room-shaped tooth. This tooth projects above and back from
the dorsal margin and is responsible for the pronounced angu-
lation at the posterior socket of the opposite valve. The hinge
of the left valve consists of a deep, anterior socket whicli is
open to the interior in front. It is flanked behind by a narrow,
high, pointed, almost blade-like tooth, which is distinctly sep-
arated from the dorsal margin by a well defined groove. This
groove, or incised line, extends along the edge of the dorsal
margin all the way from the anterior socket to the posterior
socket. Below the groove lies a heavy, thick bar, the anterior
end of which is downward and outwardly curved to form
the previously mentioned blade-like tooth. The posterior
cardinal angle is occupied by a deep, oval, oblique socket,
flanked on either side by slight swellings of the margin.
Dimensions of Cotype No. 1014: length, 0.51 mm.; height,
0.28 mm.; thickness, 0.22 mm.
Cotypes Nos. 1014 and 1015 came from the Choctawhatchec
Miocene near Ward, Florida, K. E. Young Locality 34. Para-
type No. 1016 came from the Arca zone of the Choctawhatchee,
Locality 40. The species is rare in the Area zone, but is much
more common in the upper part of the Choctawhatchee. It
has not as yet been observed in the Caloosahatchee Pliocene.

Genus CYTHERETTA Muller
Cytheretta bassleri Howe, n. sp.
Plate III, figures 21, 22.
Carapace elongate, ovate, highest and thickest near the
posterior. Dorsal margin gently curved upward; the ventral
margin slightly concave immediately in front of the center.
The anterior end of the right valve obliquely rounded, pro-
duced ventrally. The posterior end subacute just above the
middle. At either end of the dorsal margin there is a concave
notch for the overlap of the cardinal projections of the dorsal
margin of the opposite valve. The outline of the left valve is
nearly oblong ovate. The valves are ornamented near the




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 33

center by fine, sinuous lines, arranged in an obliquely longi-
tudinal direction. Viewed from the inside, the valves are only
moderately deep and the margins are flanked by the char-
acteristic marginal area of the genus. The right valve pos-
sesses a raised rim immediately inside and parallel to the
outer margin around the anterior, ventral and posterior sides.
The hinge of the right valve consists of a strong, blunt, an-
terior tooth, behind which is a much smaller oblique socket,
the posterior side of which continues as a narrow groove be-
neath the straight dorsal margin to the posterior cardinal
angle. There is also a narrow, blade-like tooth which parallels
the posterior slope. The hinge of the left valve is identical
of that of Cytheretta burnsi.
Dimensions of Holotype No. 1059: length, 1.14 mm.; height,
0.55 mm.
This species is based on numerous specimens from the Arca
zone at Locality 40. This species is closely related to Cytli'ere
inaequivalvis Ulrich and Bassler which occurs abundantly in
the Shoal River Miocene of Florida. The fine, longitudinal
lines, which decorate the central portion of the carapace,
easily separate it from that species, however. There is another
variant of it in the Upper Choctawhatchee of Ward, Florida,
the ventral side of which species is longitudinally striate
throughout.
Cytheretta burnsi (Ulrich and Bassler).
Plate II, figures 12-14, 17, 20; Plate IV, figures 14, 21.
Cythere burnsi Ulrich and Bassler, Md. Geol. Surv., Mio. Rept., 1904,
p. 103, pl. 36, figs. 34-39.
Carapace elongate ovate, highest and thickest near the
posterior end, the dorsal margin straight, the ventral margin
sinuous, the anterior and posterior ends broadly rounded. The
central part of the valves is ornamented by a reticulate pattern
of pits and ridges; many of the pits occurring in pairs and tehiil-
ing to be hexagonal in outline and the sculpture being longi-
tudinal in its arrangement. The left. valve is larger than the
right and overlaps it, particularly at the cardinal angles.
Viewed from the inside, the valves are moderately deep with
a broad marginal area, the inner margin of the anterior end
possessing the characteristic "S" shape of the genus. The
radial pore canals are very elongate and fairly numerous.
On the anterior end they radiate from a point just in front of
the muscle scars. The outer edge of the right valve is thick-





34 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

ened and sharp and slightly keeled toward the center of the
ventral margin. In the left valve there is a faint lipline which
lies just within the outer margin. The hinge of the right
valve consists of a strong anterior tooth, shaped like a pointed
triangular pyramid. Behind it lies a deep socket open to fhe
interior. From the posterior side of this socket, a shallow
groove extends half-way back along the hingeline. The edge
of the dorsal margin is straight and carries a faint groove.
The posterior tooth is strong, rounded, oblique and recurved
in the direction of the posterior extremity. The hinge of the
left valve consists of large terminal sockets which are at least
partially open to the interior. The anterior socket is flanked
in front by a strong, tooth-like projection of the dorsal mar-
gin; behind by a heavy, blunt, inwardly deflected tooth. The
posterior socket is flanked behind and partially covered by a
long pointed fold of the margin. Between the sockets there is
a narrow, minutely crenulate, straight bar, separated from the
dorsal margin by a faintly incised line.
Dimensions of Plesiotype No. 1034, a left valve: length, 1.28
nim.; height, 0.66 mm.; and Plesiotype No. 1035, a right valve:
length, 1.24 mm.; height, 0.63 mm.
Both Plesiotypes are from the Area zone of the Choctaw-
hatchee, Locality 41. This species occurs in all the Arca
zone localities.

Cytheretta karlana Howe and Pyeatt, n. sp.
Plate I, figures 30, 34; Plate III, figures 3, 4.
Carapace in side view sub-rectangular, highest anteriorly.
Dorsal margin straight or very slightly convex; ventral margin
slightly concave. Anterior outline broadly and obliquely
rounded and produced ventrally. Posterior end narrower,
smooth, rounded and faintly denticulate in the left valve; pro-
duced, sub-angulate and bluntly denticulate in right valve.
Left valve larger than the right and overlapping it at both
ends of the hinge line and at the middle of the ventral mar-
gin. The surface covered with a reticulate pattern of elongate
pits which are arranged in rows more or less concentric to the
middle. The ridges between the rows of pits are mostly low
and rounded, but several of them are more prominent than
the others and these, tending to converge toward the posterior
end, are responsible for the principal irregularities in the
pattern. The valves are tumid, being very strongly inflated




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 35

ventral and posterior to the middle. Viewed from the inside,
the valves are moderately deep, thick and smooth. The mar-
ginal areas are broad, the inner margin extending far into the
interior of the carapace and forming an "S"-shaped outline
in the interior as it extends from a point below the anterior
tooth to a point above the middle of the ventral margin. The
species is composed of such dense material that the radial pore
canals could not be discerned. The outer margin of the right
valve is sharp and slightly keeled toward the middle of the
ventral side and when it approaches the posterior end, a sharp
rim turns directly up, leaving a flattened area behind it. The
outer margin of the left valve is marked by a faint lip-line.
The hinge of the right valve consists of a high, strong, pyia-
midal anterior tooth, behind which is a deep socket. From this
socket extends a deep, straight groove below a narrow bar to
the anterior cardinal angle. This bar is separated from the
dorsal margin by a wide, shallow depression. The posterior
tooth is ovate in outline, high and recurved toward the poste-
rior. The hinge of the left valve consists of a deep, pointed
anterior socket, flanked in front and behind by tooth-like
lobes of the dorsal margin. It is partially closed by a thick-
ened rim. The posterior socket is almost identical, but smaller.
Between these sockets the dorsal margin is thin and sharp.
Dimensions of Cotype No. 1045: length, 0.95 mm.; height,
0.50 mm.; thickness, 0.47 mm.
Named in honor of Karl E. Young, who supplied so much
Florida material used in this report.
All figured specimens are from the Chipola Miocene, Lo-
cality 10.
Cytheretta karlana Howe and Pyeatt, var. choctawhatcheensis Howe
and Taylor, n. var.
Plate I, figures 28, 29, 33.
This variety differs from the typical species in being smaller
and much higher near the posterior end, particularly in the
left valve. The anterior end is more. regularly rounded and
the hinge is much more delicate. The dorsal margin of the
right valve is much lower and the groove above the dorsal bar
is narrow instead of being wide. The description is based on
six specimens found in the Arca zone of the Choctawhatchee
at Locality 40. This variety has not been observed elsewhere.
Dimensions of Cotype No. 1019: length, 0.88 mm.; height,
0.50 mm.; thickness, 0.42 mm.





36 FLORIDA GEOLOGICAL SURVEY-BULLETIN THIRTEEN

Genus CYTHERURA Sars.
Cytherura wardensis Howe and Brown, n. sp.
Plate 1, figures 23, 27; Plate IV, figure 19.
Carapace small, elongate, sub-quadrangular in side view,
of about same height throughout the length, thickest toward
the posterior, valves sub-equal. Dorsal margin high and
straight. Ventral margin somewhat sinuate and, in general,
parallel to the dorsal margin. Anterior end rounded, com-
pressed; posterior end compressed and marked by a distinct
caudal process situated slightly above the middle and turned
up slightly toward the dorsal side. Surface marked with fine
reticulations. There is a low sulcus just in front of the middle
and a small glassy tubercle just below the anterior angle.
Surface drops gently toward the dorsal margin, drops off
sharply to the ventral margin, forming a broad, flattened ven-
tral surface, longitudinally striated. Ventral margin keeled,
especially toward the posterior, the keels of the two valves
forming a sharp ridge where the valves meet. Hinge structure
imperfectly developed, apparently consisting in the left valve
of two terminal teeth connected by a lower bar; in the right
valve, two rimmed sockets connected by a faint groove.
Dimensions of Cotype No. 1075, K. E. Young Locality 34, at
which place the species is common: length, 0.52 rmm.; height,
0.29 mm.; thickness, 0.27 mm.
A single right valve of this species was found in the Arca
zone of the Choctawhatchee, Locality 15.
Genus PARACYTHERIDEA Muller.
Paracytheridea chipolensis Howe and Stephenson, n. sp.
Plate III, figures 5, 6.
The carapace is elongate, strongly and irregularly alate,
with a low, broad, swollen node just in front of the middle, an-
other near the dorsal margin in front of the posterior cardinal
angle (this swelling is so great that in side view it obscures
about one-third of the hinge line), a small one immediately
below and behind it and a high, pointed ala on the posterior
end of the well defined ventral ridge. This ridge bifurcates
just in front of the middle, so that one portion crosses the sub-
central node, the other continues straight along the ventral
side. The posterior slope of the ala carries a small carina and
behind it there is a short spine on the ventral margin. The
dorsal and ventral margins:are nearly straight and converging;
the anterior end is broadly rounded; the posterior end is dis-




CHOCTAWHATCHEE OSTRACODA OF THE ARCA ZONE 37

tinguished by a prominent dorsally flexed caudal process in
the right valve, which is concavely truncate behind. The
posterior end of the left valve is subangulate. It is obliquely
truncate in the dorsal and ventral thirds and vertically trun-
cate behind. The eyespots are fairly small and situated im-
mediately below the anterior cardinal angle. Viewed froni the
inside, the valves are irregularly deep, the margin of the right
valve carries a faint lip-line near the outside. Both valves
are slightly flanged just in front of the middle of the ventral
margin. The marginal area is narrow and is traversed by only
a very few small radial pore canals. The hinge of the rfght
valve consists of a long, straight, narrow, crenulate groove
immediately below the dorsal margin. Below each end of this
groove there is a narrow, curved, prominent, crenulate cusp.
The hinge of the left valve consists of two, terminal, deep,
crenulate sockets at the cardinal angles, over which the dorsal
margin is gently arched. Between these sockets, the dorsal
margin is straight, narrow, sharp and crenulate.
Dimensions of Cotype No. 1047, a right valve: length, 0.66
mm.; height, 0.36 mm.; and Cotype No. 1046, a left valve:
length, 0.70 mm.; height, 0.38 mm.
These Cotypes are from the Chipola Miocene, Locality 10.
This species, with minor variations, is found also in the
type Oak Grove, Locality 26, and in the Shoal River Miocene,
Locality 28. In the Area zone of the Choctawhatchee, how-
ever, it is replaced by Paracytheridea nodosa (Ulrich and
Bassler).
Paracytherida nodosa (Ulrich and Bassler).
Plate III, figure 7.
Cytheropteron nodosinm Ulrich and Bassler, Md. Geol. Surv., Mio. Rept.,
1904, p. 129, pl. 38, figs. 37-40.
This differs from the preceding species in being less reti-
culate and in lacking the divaricating rib along the ventral
keel. It is also somewhat more elongate and has a well de-
fined, oblique sulcus, which starts just behind the anterior
cardinal angle and continues to a point in front of the sub-
central node.
Dimensions of the Plesiotype No. 1048, a left valve from
the Choctawhatchee Miocene, Locality 41: length, 0.70 mm.;
height, 0.32 mm.
This species occurs rarely in all of the Area zone localities
examined.





























PLATES I-IV


L39 J








PLATE I


Figures 1-5. Cythereis exanthemata (Ulrich and Bassler), var. mary-
landica Howe and Hough, n. var. X 25. Fig. 1, Cotype
No. 893, interior of a left valve. Figs. 2, 3, Cotype No.
894, interior and exterior of a right valve. Fig. 4, Co-
tpye No. 895, exterior of a left valve. Fig. 5, Cotype No.
896, dorsal view. Calvert formation, Plum Point, Chesa-
peake Bay, Maryland.
6-12. Cythereis exanthemata (Ulrich and Bassler), var. go-
millionensis Howe and Ellis, n. var. X 33. Fig. 6, Colype
No. 897, interior of a left valve. Fig. 7, Cotype No. 897,
exterior of a female left valve. Figs. 8, 9, Cotype No. 898,
interior and exterior of a female right valve. Figs. 10,
11, Cotype No. 899, interior and exterior of a male left
valve. Fig. 12, Cotype No. 888, dorsal view. Locality 41.
13-17. Cythereis gunteri Howe and Chambers, n. sp. X 28.
Fig. 13, Cotype No. 1000, dorsal view. Fig. 14, Cotype
No. 1009, exterior of a left valve. Fig. 15, Cotype No.
1010, exterior of a right valve. Fig. 16, Cotype No. 1010,
hinge of a right valve. Fig. 17, Cotype No. 1009, hinge
of a left valve. Locality 41.


18, 20-22.



19, 24-26.


Cythereis rugipunclata (Ulrich and Bassler). X 43.
Fig. 18, Plesiotype No. 1011, dorsal view. Fig. 20, Plesio-
type No. 1012, interior of a left valve. Figs. 21, 22, Plesio-
type No. 1013, exterior and interior of a right valve.
Locality 40.
Basslerella miocenica Howe, n. sp. X 50. Fig. 19, Co-
type No. 1014, dorsal view. Fig. 24, Paratype No. 1016,
interior of a left valve. Fig. 25, Cotype No. 1014, left
valve view of a complete specimen. Fig. 26, Cotype No.
1015, interior right valve view of a complete specimen.
K. E. Young Locality 34.


23, 27. Cytherura wardensis Howe and Brown, n. sp. X 48. Fig.
23, Cotype No. 1017, interior of a left valve. Fig. 27, Co-
type No. 1018, exterior of a right valve. K. E. Young
Locality 34.


28, 29, 33.


Cytheretta karlana Howe and Pycatt, var. choclawhat-
cheensis Howe and Taylor, n. var. Figs. 28, 29, X 30;
Fig. 33, X 28. Fig. 29, Cotype No. 1019, right valve view
of a complete specimen. Fig. 29, Cotype No. 1020, in-
terior of a left valve. Fig. 33, Cotype No. 1019, dorsal
view. Locality 40.


30, 34. Cytheretta karlana Howe and Pyeatt, n. sp. X 26. Fig.
30, Cotype No. 1021, interior of a right valve from
Chipola Miocene. Fig. 34, Cotype No. 1022, interior of a
left valve from Chipola Miocene. Locality 10.


31, 32, 35-37.


Cythereis product (Ulrich and Bassler). X 30. Fig. 31,
Plesiotype No. 1023, dorsal view. Figs. 32, 36, Plesio-
type No. 1024, exterior and interior of a right valve.
Figs. 35, 37, Plesiotype No. 1025, exterior and interior of
a left valve. Locality 41.


[40




BULLETIN THIRTEEN, PLATr I


7 8


10


14 15


12





16


17' 18

fir \


20 21


23


27 28




31

t: 1Il


[41]


9
^sF B-


30


29



,V




33


37


GEOLOGICAL DEPARTMENT


'I


%/















PLATE II


Figures 1-3. Hemicythere dalli Howe and Brown, n. sp. X 50. Figs.
1, 2, Cotype No. 1026, Oak Grove Miocene, interior and
exterior of a right valve. Fig. 3, Cotype No. 1027, Oak
Grove Miocene, interior of a left valve. Locality 29.
4, 7. Hemicythere dalli Howe and Brown, var. redbayensis,
n. var. X 40. Fig. 4, Holotype No. 1028, exterior of
right valve. Fig. 7, Holotype No. 1028, dorsal view.
Locality 40.
5, 8, 9. CUiheromorpha warneri Howe and Spurgeon, n. sp. X 56.
Figs. 5, 8, Cotype No. 1029, exterior and interior of a left
valve. Fig. 9, Cotype No. 1030, interior of a right valve.
K. E. Young Locality 34.
6, 10. Hemicythere sellardsi Howe and Neill, n. sp. X 50.
Fig. 6, Holotype No. 1031, exterior of a left valve. Fig.
10, Holotype No. 1031, dorsal view. Locality 40.
11. Cylheridea choclawhalcheensis Howe and Stephenson,
n. sp. X 28. Holotype No. 1032, exterior of a right valve.
Locality 41.


12-14, 17, 20.




15, 16, 18.




19, 21-24.


CyUherella burnsi (Ulrich and Bassler). X 26. Figs.
12, 20, Plesiotype No. 1035, exterior and interior of a
right valve. Figs. 13, 17, Plesiotype No. 1034, exterior
and interior of a left valve. Fig. 14, dorsal view drawn
from Plesiotype No. 1034 and No. 1035. Locality 41.
Cytheridea floridana Howe and Hough, n. sp. Figs. 15,
18, X 30; Fig. 16, X 28. Fig. 15, Paratype No. 1036,
interior of a right valve. Fig. 16, Holotype No. 1037,
exterior, right valve view. Fig. 18, Paratype No. 1038,
interior of a left valve. Figs. 15, 18, Locality 41; Fig.
16, Locality 15.
Cythereis (Plerygocythereis) corntla, var. americana
(Ulrich and Bassler). X 39. Fig. 19, Plesiotype No.
1039, dorsal view. Fig. 21, Plesiotype No. 1042, interior
of a left valve. Figs. 22, 23, Plesiotype No. 1041, interior
and exterior of a right valve. Fig. 24, Plesiotype No.
1040, exterior of a left valve. Locality 28.


[42]




GEOLOGICAL DEPARTMENT


(


ii


1 2


3 -rx


5 6


8 9


22 23


[ 43 J


7


20


BULLETIN THIRTEEN-III PLATE I1








PLATE III
Figures 1-2. Cyflheridella chambers Howe, n. sp. Fig. 1, X 38; Fig.
2, X ,13. Holotype No. 1043, interior and exterior of a
right valve. Locality 41.
3-4. Cytherella karlana Howe and Pyeall, n. sp. X 29. Fig.
3, Cotype No. 1045, Chipola Miocene, dorsal view. Fig.
4, Cotype No. 1045, exterior of a right valve of com-
plete specimen. Locality 10.
5-6. Paracytheridea chipolensis Howe and Stephenson, n.
sp. Fig. 5, X 44; Fig. 6, X 38. Fig. 5, Cotype No. 1046,
Chipola Miocene, exterior of a left valve. Fig. 6, Co-
type No. 1047, Chipola Miocene, exterior of a right
valve. Locality 10.
7. Paracllheridea nodosa (Ulrich and Bassler). X 40.
Plesiotype No. 10,18, exterior of a left valve. Locality
41.
8-10. Cy/lheideis ashermani Ulrich and Bassler. X 22. Fig.
8, Plesiotype No. 10,19, interior of a left valve. Figs.
9, 10, Plesiotype No. 1050, exterior and interior of a
right valve. Locality 40.
11-14. Cyllherideis ilrichi Howe and Johnson, n. sp. X 27.
Figs. 11, 13, Cotype No. 1053, exterior and interior of
a left valve. Figs. 12, 14, Cotype No. 1052, exterior and
interior of a right valve. Locality 40.
15, 16, 20, 23. Cllherideis fabula Howe and D)ohm, n. sp. X 25. Figs.
15, 23, Cotype No. 1054, interior and exterior of a r1ght
valve. Fig. 16, Colype No. 1055, interior of a left valve.
Fig. 20, Cotype No. 1056, dorsal view. Locality 40.
17-19. Cllthereis /garrelli Howe and McG(uirt, n. sp. X 32.
Figs. 17, 18, Cotype No. 1057, interior and exterior of
a left valve. Fig. 19, Cotype No. 1058, interior of a
iight valve. Locality 41.
21, 22. C(ltherella basslcri Howe n. sp. X 30. Ilololype No.
1059, exterior and interior of a right valve. Locality
'10.
2.1-26. Cy!hereis vaulhaniM (Ulrich and Bassler). X 45. Fig.
24, lPlesiotype No. 1061, exterior of a left valve. Fig.
25, Plesiotype No. 1062, interior of a right valve. Fig.
26, Plesiotype No. 1063, interior of a left valve. Lo-
cality 34.
27-30. Ciylherideis aglricola Howe and Hadley, n. sp. X 37.
Figs. 27, 28, Cotype No. 1064, exterior and interior of a
right valve. Figs. 29, 30, Colype No. 1065, interior
view of the posterior and anterior ends of a left valve,
showing prominent flanges. Locality 41.
31-34. Ilemicy!lhere conradi Howe and McGuirt, n. sp. X 42.
Fig. 31, Colype No. 1066, dorsal view. Fig. 32, Cotype
No. 1066, exterior, left valve. Fig. 33, Cotype No. 067,
interior of a left valve. Fig. 34, Cotype No. 1068, in-
lerior of a right valve. Locality 40.


[44]





BULLETIN THIIITEEN, PLATE' III


2


II 12


13


25 28


29 30


31


[45]


8




9

7-


20


GEOLOGICAl DEPARTMENT







Figure 1.


PLATE IV
Cythereis gunteri Howe and Chambers, n. sp. X 40. Co-
type No. 1009, right valve, showing radial pore canals.
Locality 41.


2. Cytherideis fabula Howe and Dohm, n. sp. X 42. Cotype
No. 1069, right valve, showing radial pore canals. Lo-
cality 41.
3. Cythereis exanthemata (Ulrich and Bassler), var. gomillion-
ensis Howe and Ellis, n. var. X 40. Cotype No. 898, right
valve, showing radial pore canals. Locality 41.
4. Cytheromorpha warneri Howe and Spurgeon, n. sp. X 42. Co-
type No. 1070, dorsal outline. K. E. Young Locality 34.
5, 15. Cythereis garetti Howe and McGuirt, n. sp. X 28. Fig. 5,
Cotype No. 1058, right valve, showing radial pore canals.
Locality 41. Fig. 15, muscle scar pattern.
6, 10. Cytheridea floridana Howe and Hough, n. sp. Fig. 6, X 37,
Paratype No. 1071, anterior end of a left valve, showing
radial pore canals; Locality 41. Fig. 10, X 22, Holotype
No. 1037, dorsal outline; Locality 40.
7. Cythereis exanthemata (Ulrich and Bassler), var. mary-
landica Howe and Hough, n. var. X 35. Cotype No. 895,
a left valve showing radial pore canals, Calvert formation,
Plum Point, Chesapeake Bay, Maryland.


8. Cytherideis agricola Howe and Hadley, n. sp.
type No. 1072, dorsal outline. Locality 40.


9. Cytheridea
sp. X 41.
pore canals


X 32. Co-


choctawhatcheensis Howe and Stephenson, n.
Holotype No. 1032, right valve, showing radial
and muscle scars. Locality 41.


11, 12. Cythereis product (Ulrich
type No. 1024, right valve,
Locality 41.


and Bassler). X 37. Plesio-
showing radial pore canals.


13. Cythereis vaughani (Ulrich and Bassler). X 40. Plesio-
type No. 1073, dorsal view. K. E. Young Locality 34.
14,21. Cytheretta burns (Ulrich and Bassler). Fig. 14, X 46;
Plesiotype No. 1074, left valve showing radial pore canals;
Calvert formation, Miocene, Plum Point, Maryland. Fig.
21, X 50; Plesiotype No. 1034, left valve showing radial
pore canals; Locality 41.
16, 20. Cytheridella chambers Howe, n. sp. X 43. Fig. 16, muscle
scar pattern. Fig. 20, Holotype No. 1043, dorsal outline
of a right valve. Locality 41.
17. Hemicythere conradi Howe and McGuirt, n. sp. Muscle
scar pattern.


18. Hemicythere dalli Howe and Brown, n. sp. X 40.
No. 1027, left valve, showing radial pore canals.
29.


Cotype
Locality


19. Cytherura wardensis Howe and Brown, n. sp. X 32. Co-
type No. 1075, dorsal outline. K. E. Young Locality 34.
22, 23. Cythereis rugipunctata (Ulrich and Bassler). X 32. Fig.
22, Plesiotype No. 1012, outline, of left valve. Fig. 23,
Plesiotype No. 1013, outline of right valve. Locality 40.
24. Cythereis (Plerygocythereis) cornula, var. americana
Ulrich and Bassler. X 40. Plesiotype No. 1039, posterior
outline showing lateral alae. Locality 28.
[ 46]




GEOLOGICAL DEPARTMENT


BULLETIN THIRTEEN, PLATE IV


I 2


4











8


10


II 12


19





c


23


0.
-


17










22


24


[47]


I-,
C

20