ANATINIDA. il 
with an obscure lunette; posterior hinge-line with a narrow 
interior ridge ; ligament external. Epidermis strongly wrinkled. 
Animal unknown; probably had a closed mantle and respi- 
ratory siphons. 
CyatHoponta, Conrad, 1849. 
Distr.—4 sp. China, L. Cal., sacri OF gales Ads. 
and Reeve (cvili, 74). = 
Shell like Anatina in inant: saledes rita a broad, not very 
projecting fosset, which is carinated near the mar gin; muscular 
impressions rounded, indistinct ; pallial impression with a large, 
rounded sinus.” 
GoniomyA, Agassiz, 1838. 
Syn.—Lysianassa, Munst., 1838. 
Distr.—Cretaceous and Jurassic. G. Duboisi, Agass. (evili,75). 
Shell oblong, rather compressed, thin, surface marked about 
the middle of the flanks with angularly bent striz or ribs; 
hinge without teeth; a slight incision below the beaks, and 
slightly thickened nymphez beyond the same for the attachment 
of a ligament are present. 
Cu@nomyA, Meek, 1865. 
Syn. —-Anoplomya, Krauss. 
Distr _—Cretaceous, Jurassic. C. Cooperi, Meek (cix, 84). 
Shell oblong, equivalve, inequilateral, thin, concentrically 
striated or ribbed, with an oblique process below the beaks of 
each valve, probably supporting an internal cartilage ; nymphee 
prominent for the attachment of an external ligament; sinus 
very deep and usually angular. 
Terquem has sufliciently proved that this a good genus, and 
must be kept separate from Homomya, Myacites and Panopea, 
which it externally greatly resembles. 
Shell much like Anthracomya, of thin structure, more or less 
compressed, posteriorly gaping. 
PuoLapomya, G. Sowerby. 
Syn.—Procardia, Meek. 
Distr.—2 sp. West Indies, off Rhode Island. P. candida, 
Sowb. (eviii, 76, 77). Fossil, 160 sp. Li ; United States, 
Europe, Algeria, Thibet. P. exaltata, Agass.(cix, 85). P. glabra, 
Agass. (cix, 86). 
Shell obiong, equivalve, ventricose, gaping behind ; thin and 
translucent, ornamented with radiating ribs on the sides ; liga- 
ment external ; hinge with one obscure tooth in each valve; 
pallial sinus large. 
Animal with a single gill on each side, thick, finely plaited, 
grooved along its free border, the outer lamina prolonged dor- 
sally ; mantle with a fourth (ventral) orifice —OweEn. 
