•MONOGEAPH 



AMERICiN CORBICULADJ:. 



Family CORBICULAD.^.^ 



Les conques (ex parte), Lamarck, 1809.— Cyclad&es, Rafinesque, 1815.— 

 Les conques Jiuviatiles, Lamarck, 1818.— Feneriada?, Gray, 1818.— 

 Cydadia, Rafinesque, 1818.— Z.es C^ckdes, Ferussac, 1822.— C;/c/a- 

 dine, Latreille, \81h. — Cydadx, Fleming, 1828. — C^/r/ar/fa, De- 

 SHATES, 182,0.— Cyrenidse, Gray, 1840.— Q/c/ac?acea, Hinds, 1844.- 

 Cijdasidse, D'Orb., l8Aio.—Corbiculadse, Gray, 1847. 



Animal regular, mantle witli tlie lobes free in front and at 

 the base, ending in two short syphons united at their base 

 and sometimes to the extremity; foot triangular, compressed, 

 tongue shaped or cylindrical; tentacles of the mouth small, 

 triangular, pointed ; gills broad, unequal, united behind. 



Shell regular, oval or subtrigonal, covered with an epi- 

 dermis; hinge with two or three teeth in each valve; lateral 

 teeth two, simple or striated; palleal impression simple or 

 with a short sinus ; ligament external. 



The Corbiculadaj are divided into the following six genera : — 



A. Cardinal teeth 3, 3, anterior of right and posterior of left valve 

 smallest. Shell solid. 



1. Corhicula, Megerle, 1811.— Shell subcordate ; lateral teeth com- 



pressed, subequal, finely striated. 



2. Batissa, Gray, 1852.— Shell subcordate ; lateral teeth compress- 



ed, anterior very short, posterior elongate. 



3. Velorita, Gray, 1834.— Shell cordate, triangular, thick, teeth 



large, lateral very finely striated, anterior very large, regular, 

 hinder elongate, compressed. 



4. Cyrena, Lamarck, 1818. Shell subcordate ; lateral teeth smooth, 



front roundish, hinder rather compressed. 



' Proc. Zool. Soc. XV, 1847, 184. 



