162 SEMELID-aS. 



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 

 teeth short, smooth, subequal ; siphonal inflection distinct. P. 

 erycina, Lara, (ex, 27). 



TARiA, Gra3\ Shell oblong, subequilateral, attenuated pos- 

 teriorly ; posterior margin carinated ; lateral teeth very narrow. 

 P. lata, Desh. (ex, 28). 



CERONiA, Gray, 1849. Shell oval, 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. P. cuneata, Lam. icx, 31). 



DAViLLA, Gray, 1849. Shell cuneiform-orbicular, somewhat 

 truncated posteriorly ; lateral teeth unequal, the anterior narrow, 

 perpendicular. P. crassula, Desh. (ex, 32). 



MACTROPSis, Conrad, 1865. Resembles Anapa ; it has in the 

 left valve either one bifid or two diverging cardinal teeth, a 

 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. P. Grayi, Lea. 



Ervilia, Turton. 



Etym. — Ervilia^ diminutive of ervimi, the bitter-vetch. Lentil- 

 shell. 



Distr.—% sp. West Indies, Britain, Canaries, Mediterranean, 

 Red Sea, W. Coast America ; 50 fathoms. E. castanea, Mont, 

 (ex, 33). 



Shell minute, oval, close ; cartilage in a 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. 



Family SEMELID^. 



Shell thin, subequivalve, gaping and usuall}^ flexuous posteri- 

 orly ; external 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. 



