CYTIIEREA. 395 



cimens were mistaken for a distinct living species by Dr. 

 Turton, and named Venus anea. It is also found in the 

 Newer Pliocene strata of Sicily. 



CYTHEREA. Lamarck. 



Shell solid, cquivalve, inequilateral, closed, usually more 

 or less transversely oblong, with slightly prominent and 

 recurved beaks. Surface sometimes sulcated or striated 

 transversely, usually nearly smooth. Muscular impressions 

 ovate ; pallial sinus wide, ovate, obtusely pointed. Mar- 

 gins always smooth. Hinge composed usually of four di- 

 verging teeth in one valve, and three in the other, with 

 corresponding pits. Ligament external, rather long. 



Animal oblong, with its mantle freely open, and plain at 

 the margins. Foot large, linguiform, not furnished with a 

 byssal groove ; siphons united nearly to their extremities, 

 orifices of both with (simjjle) cirrhi. 



This genus is rejected by Deshayes, Rang, and D'Or- 

 bigny, and many modern malacologists, on the plea of its 

 being entirely artificial. It is maintained by others as a 

 convenient section of a group containing an immense and 

 inconvenient number of species, which the genus Venus 

 in the sense used by the authors mentioned is. In a 

 scientific treatise, such as Ave wish this to be, no such plea 

 could be admitted. We adopt this Lamarckian group on 

 higher grounds, and maintain it because it includes a very 

 natural assemblage of forms, presenting certain important 

 characters in common, both of shell and animal, sufficiently 

 separating them from the true Veneres. In our seas we 

 have only a single representative of this beautiful section — 

 that one among our most beautiful indigenous mollusks. 

 In tropical seas they abound, and are remarkable for ele- 



