NO. 1312. SYNOPSIS OF THE VENERID.E—DALL. 365 



Genus VENERUPIS Lamarck, 1818. 



Type, Yenns irn!< Linnanis. 



Valves elongate and .subquadrate; sculpture radial with distant, 

 prominent concentric lamellation; lunule and right half of the 

 ■escutcheon absent, left half of the latter detined by a keel; ligament 

 exposed; the pallial sinus short, ascending, free, blunt in front; inter- 

 nal margins smooth in the type species; there are three cardinals in 

 each valve, the anterior right and posterior left entire and slender, 

 the others broad and deeply bitid; the siphons are long, united for 

 half their length and with papillose orifices. 



The species of this group are nestlers and often deformed. They 

 have been much confused with species of Pcti'icolidw. 



The name has been spelled Yenerirtqjis by Sowerby and Venererupes 

 by Swainson. Petrifora Latreille, 1827, may be identical, but Irus 

 Oken, 1815, is a sj'nonym of Saxicava. 



SulafkiTiily G-OEMliyEIN".^. 



SPECIES VIVIPAROUS, MINUTE. 



Genus GEMMA Deshayes, 18SS. 



Type, Venus geiinna Totten. 



Shell subtrigonal, with concentric sculpture, a short external liga- 

 ment, and large lunule, but no escutcheon; inner margin of valves 

 cienate; pallial sinus distinct, small, triangular; siphons separate, the 

 branchial longer and papilliferous; an elongated posterior left and 

 anterior right lateral tooth received into a groove on the margin of 

 the opposite vahe; foot linguiform, not byssiferous. 



The genus l)elongs to the Atlantic coast of North America, but has 

 been introduced on the Pacific coast with seed 03'sters. It is repre- 

 sented in the eastern Tertiaries. 



It is Tottrnla Perkins, 18(59. 



Genus PARASTARTE Conrad, 1862. 



Ty})e, Astaiic triquetiu Conrad. 



Shell trigonal, with prominent elevated l)eaks, ecpiilateral, heavy, 

 with a short ligament and large lunul(\ but no escutcheon; surface 

 smooth, l)rightly colored, with a vernicose periostracum; internal 

 margins crenate; pallial line slightly tiexuous behind, but with no 

 d(>tinite sinus; right ^•alve with a strong middle cardinal and two feeble 

 ones; left valve with two strong cardinals, but no lateral teeth; dorsal 

 margins outside the hinge plate feebly grooved to receive the edges of 

 th(> opposite valve. 



This genus is confined to the coast and Tertiaries of the southeastern 

 United States. 



It is Callicistronia Dall, 1883, olim. 



