Late Cenozoic Ostracodes — Holden 
29 
TABLE 6 
Dimensions of Quadracythere hornibrooki N. sp. 
SPECIMEN 
LENGTH 
WIDTH 
HEIGHT 
Holotype usnm 648758 (left valve) T-12 
0.77 
0.21 
0.50 
Paratype usnm 648759 (left valve) T-12 
0.75 
0.22 
0.50 
Paratype sdnh 1048 (right valve) T-12 
0.80 
0.22 
0.52 
Paratype sdnh 1049 (left valve) T-12 
0.80 
0.25 
0.50 
Paratype USNM 648760 (right valve, young) T-12 
0.69 
0.18 
Paratype usnm 648761 (left valve) T-12 
0.77 
0.26 
0.52 
marginal denticulations and are more ovate in 
dimensions: 
lateral outline. 
SPECIMEN 
LENGTH 
WIDTH 
HEIGHT 
Holotype usnm 648771 
Genus Loxoconcha Sars, 1866 
(left valve $ ) T-12 
Paratype sdnh 1050 
0.58 
0.20 
0.35 
Loxoconcha batei n. sp. 
(right valve $ ) T-12 
Paratype sdnh 1051 
0.58 
0.18 
0.33 
Figs. 20 a-b 
(left valve $ ) T-12 
0.53 
0.20 
0.34 
diagnosis: Straight dorsal margin; evenly 
inflated carapace; extremely complicated orna- 
Paratype usnm 64 8772 
(left valve $ ) T-12 
0.59 
0.20 
0.36 
mentation of high, flat-topped discontinuous 
distribution: As fossils from T-l (1 valve), 
ridges surrounded by less pronounced network 
T-7 (1 valve), T-ll 
(3 valves), T-12 (16 
of reticulations. 
description: In lateral view: carapace ob- 
long; dorsal margin straight; ventral margin 
gently convex, curving upward posteriorly 
forming subtle arcuate posteroventral ridge ; 
anterior margin usually broadly rounded; pos- 
terior margin straight, sloping upward 60° in 
ventral half; ornamentation distinctive: heavy 
discontinuous flat-topped ridges and flat-topped 
spines rising high above a coarsely reticulate 
lower surface; large low eye tubercles present. 
Carapace evenly inflated in dorsal view. 
Hinge gongylodont: left valve anterior ele- 
ment a short rounded tooth, postadjacent socket 
and smaller tooth; median element a crenulate 
bar; posterior element a very small socket, round 
postadjacent tooth, and larger socket, sockets 
interconnected. Well-developed accommodation 
groove present above median element of left 
valve. 
Adductor muscle scar pattern an arcuate row 
of four smaller quadrate scars on slight median 
ridge (not expressed as an external sulcus), 
lowest scar in front of top three scars ; quadrate 
antennal scar in front of top two adductor 
scars ; radial pore canals not observed ; no vesti- 
bules present; heavy continuous selvage along 
duplicature of left valve with corresponding 
heavy groove in right valve. 
valves; 1 entire), and S-23 (1 valve). 
discussion: The ornamentation of this 
species is very distinctive. The high ridges show 
no organized pattern but are flat-topped and 
widest on top, forming a distinct upper surface 
above and apart from the lower reticulations. 
The species is named in honor of Dr. R. H. 
Bate of the British Museum (Natural History). 
Loxoconcha condyla n. sp. 
Figs. 21 a-b 
diagnosis: Straight dorsal margin; orna- 
mented with small poorly defined reticulations; 
compressed postroventral margin beneath a high 
caudal process ; weak pointed posterodorsal 
tubercle. 
description: In lateral view: carapace elon- 
gate, length about twice the height; dorsal mar- 
gin straight, anterior margin somewhat obliquely 
rounded; ventral margin beneath high caudal 
process constricted into posteroventral keel. In 
dorsal view: carapace sublenticular, compressed 
behind poorly developed dorsal tubercles near 
posterior; greatest width central at broad sub- 
central swelling. Ornamentation of poorly de- 
fined small reticulations (or large pits) ; antero- 
marginal ridge grooved by row of small pits; 
eye tubercles well developed. 
