22 
PACIFIC SCIENCE, Vol. XXI, January 1967 
Fig. 14. Hemicythere obesa n. sp. a-b, Holotype USNM 648744; a, side view of entire carapace; b, dorsal 
view of entire carapace; c, Paratype sdnh 1042; internal view of right valve; adductor scars in white, d, Para- 
type usnm 648745 ; muscle scar pattern of right valve; adductor scars in white. 
The hinge differs from the typical Hemi- 
cythere amphidont type by being deeply notched 
beneath the posterior tooth. The species is 
named with reference to its highly inflated 
carapace. 
Hemicythere sp. 
Figs. 15 a—c 
description: In lateral view: carapace sub- 
oval, dorsal margin straight, slightly converg- 
ing posteriorly with straight ventral margin; 
anterior and posterior margins broadly rounded, 
dorsal part of anterior margin more flattened 
than ventral part, caudal process absent. Orna- 
mentation distinctive; entire surface covered by 
distinctly flat-topped ridges continuous in cen- 
trolateral parts of carapace and discontinuous 
near margins of carapace; well-defined concen- 
tric pattern centered around area coinciding 
with internal adductor-antennal muscle scar 
area; eye tubercles low, indistinct, but well- 
developed internal ocular sinuses are present. 
