162 SEMELIDA. 
lateral teeth in each valve; muscular scars deep; pallial sinus 
small. 
Animal with mantle-margins plain; siphons short, thick and 
separate, orifices cirrated, branchial cirri dendritic; foot com- 
pressed, broadly lanceolate ; gills large, unequal; palpi small. 
MESODESMA, Desh., 1830. Shell oval, subequilateral ; lateral 
tecth short, smooth, subequal; siphonal inflection distinct. P. 
erycina, Lam. (cx, 27). 
TARIA, Gray. Shell oblong, subequilateral, attenuated pos- 
teriorly ; posterior margin carinated ; lateral teeth very narrow. 
P. lata, Desh. (ex, 28). 
CERONIA, Gray, 1849. Shelloval, cuneiform; truncated behind ; 
lateral teeth subequal, compressed, coarsely obliquely striate ; 
siphonal inflection distinct. P. Jauresii, Joannis . cx, 29). 
DONACILLA, Lam., 1812. Shell elongate-cuneiform, slightly 
truncate posteriorly ; anterior lateral teeth elongated, posterior 
short; siphonal sinus distinct. P. donacilla, Lam. (ex, 30). 
ANAPA, Gray, 1849. Shell subtrigonal, ventricose, truncate 
posteriorly ; lateral teeth subequal, compressed, smooth; siphonal 
inflection obsolete. DP. cuneata, Lam. \ ex, 31). 
DAVILLA, Gray, 1849. Shell cuneiform-orbicular, somewhat 
truncated posteriorly ; lateral teeth unequal, the anterior narrow, 
perpendicular. P. erassula, Desh. (ex, 32). 
MAcTROPSIS, Conrad, 1865. Resembles Anapa; it has in the 
left valve either one bifid or two diverging cardinal teeth, 
distinct anterior, but less prominent posterior lateral tooth ; 
possesses a small obtusely angular pallial sinus; in external 
appearance it looks very much like a Crassatella. Eocene; N. 
Am. PP. Grayi, Lea. 
ErviiiA, Turton. 
Etym.— Ervilia, diminutive of ervum, the bitter-vetch. Lentil- 
shell. 
Distr.—2 sp. West Indies, Britain, Canaries, Mediterranean, 
Red Sea, W. Coast America; 50 fathoms. . castanea, Mont. 
(ex-33): 
Shell minute, oval, close ; cartilage ina central pit ; right valve 
with a single prominent tooth in front and an obscure tooth 
behind ; left valve with two obscure teeth; no lateral teeth ; 
pallial sinus deep. 
Famity SEMELID AS. 
Shell thin, subequivalve, gaping and usually flexuous posteri- 
orly ; ener ligament short ; cartilage internal, in a cardinal 
pit. Siphons elongated, separate and divergent. 
SEMELE, Schumacher, 1817. 
Etym.—Semele, in Greek myth, the mother of Bacchus. 
