220 

 Lutraria. 



salenoides. . transverse, rugaeform striae ; foreside very long ; apex 



rounded, gaping much. . Mount Marius. 

 elliptica. . transverse striae. . very small. . Bourdeaux. 

 crassidens. . solid, opaque, substriated ; cardinal tooth thick. 



Mactra. 



deltoides. . ovato -trigonal, shorter behind ; elegantly plicated by 

 the corselet and lunule. . Grignon and Bourdeaux. 



Crassatella. 



tumida. . ovato -trigonal ; gibbous and thick with age ; the fore- 

 side angulated; base transversely sulcated; margin den- 

 tated within. 



sinuata . . obliquely trigonal ; foreside angulated, winding. . 

 Bourdeaux. 



striatula. . ovato-trigonal, with numerous fine transverse grooves 

 or striae. . St. Brieux. 



compressa. . ovato-orbiculate, rather flat ; angulated forwards ; 

 transverse striae, most prominent at the base. . Grignon and 

 Courtagnon. 



lamellosa. . transversely oblong, with distant erect lamelliform 

 ridges ; valves crenulated. . Grignoh. 



trigonata. . orbicularly trigonal ; transversely grooved ; base 

 rather smooth ; border smooth. . Grignon. 



latissima . . elliptical, compressed ; unequally sulcated trans- 

 versely ; border smooth. . Saint Iries. 



Erycina. 



Icevis. . ovate, polished ; striae very fine, transverse ; hinge with 



two teeth, 



pellucida. . ovato-orbicular ; with one very small tooth. 

 trigona. . ovato -triangular ; one smooth tooth. 

 inequilateral. . obovate, tumid, smooth ; two small teeth. 

 fragilis. . ovato -trans verse ; thin and pellucid ; two teeth. 

 elliptica. . depressed in the middle ; transverse striae, very fine ; 

 two hinge teeth ; pit intermediate. 



Corbula. 



gallica. . ovato-transverse ; larger valve turgid, finely striated to 

 the base, that being smooth. . Grignon. 



costulata. . the less valve with radiating longitudinal ribs ; base 

 smooth. 



rugosa. . trigonal, ventricose j thick transverse grooves ; angu- 

 lated forwards, rather pointed. . Grignon, 



striata. . ovato-transverse ; rathea beaked, elegantly striated 

 transversely. . Grignon and Courtagnon. 



Petricola. 



chamoides. . ovate, inflated, thick ; with longitudinal rugae, curled 

 and lamellated toward the margin on the upper side ; the 

 foreside widest. . Italy. 



