VENER1D.E. ni 



MAECiA, H. and A. Adams, 1854. Surface of the valves smooth. 

 V. utidulosa, Lam. (cxiii, 18). 



KATELYSiA, Romer, 185t. V. scalarina, Lam. 



ANAiTis, Romer, 185t. (Clausina, Brown.) Lieludes the 

 moderately tumid cordate forms with strong concentric lamellae. 

 F. plicata, Gmel. 



GOMPHiNA, Morch, 1855. Shell ovate, cordate, moderately 

 inflated, smooth ; hinge-teeth the same as in typical Chione. 

 Romer describes four species, and considers V. undulosa^ Lam., 

 as the type, while H. and A. Adams quote V. donacina, Chemn. 

 (cxiii, 19), as the only species, and place it as a subgenus of 

 Cytherea (= Meretrix). 



VOLUPIA, Defrance, 1829. Shell minute, Isocardia-shaped 

 concentrically ribbed, with a large lunule. V. riigosa, Defr, 

 Eocene ; Hauteville. 



PsEPHis, Carpenter, 1865. 



Distr. — 3 sp. California. P. Lordi, Carp. 



Shell thin, rounded or quadrangular, somewhat inflated ; 

 jDallial sinus small ; three elongated thin cardinal teeth in each 

 valve. Oviparous, like Sphcerium. 



Cytherea, Lam., 1805. 



Etym.— Cytherea^ from Cythera, an J^]gean island. 



Syn. — Meretrix, Lam., 1*199. Callistoderma, Poll, 1191. Cor- 

 bicula, Benson. 



Distr. — Same as Yenus. Recent 150 sp. Fossil, 80 sp. Cre- 

 taceous — . G. petechialis, Lam. (cxiii, 20). 



Shell like Yenus, oval-triangular, smooth ; margins simple ; 

 hinge with three cardinal teeth and an anterior tooth beneath 

 the lunule ; pallial sinus moderate, angular. 



Animal with plain mantle-margins ; siphons united half-way. 



callista, Poll, 1791. Shell oval, transverse, inequilateral; 

 pallial sinus suboval, profound. Mantle-margins folded and 

 cirrous above the siphons ; siphons united, cirrated at their 

 extremities. C. eryciyia^ Linn, (cxiii, 21). 



tivela, Link, 1807. (Trigona, Muhlf., 1811.) Shell triangular, 

 subequilateral, cuneiform ; three to five cardinal teeth in one 

 valve, four to six in the other; anterior lateral tooth narrow, 

 elongated, compressed; pallial impression with a short oblique 

 or sometimes horizontal sinus. 28 sp. W. Indies, Mediterra- 

 nean, Senegal, Cape, India, West America. Fossil. Miocene ; 

 Bordeaux. G. 7^adiata, Sowb. (cxiii, 22). 



pachydesma, Conr. (Trigonella, Conr., 1837.) G. crassatel- 

 loides, Conr., attains a diameter of five inches, and is very 

 ponderous. 



APHRODINA, Conrad, 1868. Shell rounded or suboval, striated 

 or sulcated ; hinge in the left valve with three diverging cardinal 



