ACEPHALA TESTACEA. 101 



a plate, and under the teeth a large cavity, which receives a part of 

 the ligament*. 



GrALATH.EA, Brug. 



The shell triangular ; three teeth on the summit of one valve, and 

 two on the other, en chevron ; the lateral plates approximated! . 



But a single species is known ; it inhabits the fresh waters of 

 the East Indies. 



It is here also that must be placed another genus separated from 

 Venus, the 



Cordis, Cuv. — Fimbria, Megerl. 



Marine testaceous Acephala, transversely oblong, which have also 

 stout middle teeth, and well marked lateral plates ; their external 

 surface is furnished with tr nsverse ribs so regularly crossed by rays, 

 that it may be compared to wicker-work. 



The impression of their mantle exhibiting no flexure, their tubes 

 must be short |. 



Some of them are fossil§. In the 



Tellina, Lin. 



There are in the middle, one tooth on the left and two teeth on the 

 right, frequently forked, at some distance before and behind, on the 

 right valve, a plate, which does not penetrate into a cavity of the 

 opposite one. There is a slight plica near the posterior extremity of 

 the two valves, which renders them unequal in that part, where they 

 are somewhat open. 



The animal of the Tellinae — PERONiEA,Poli, — like that of the Dona- 

 ces, lias two long tvibes for respiration and for the anus, which with- 

 draw into the shell, and are concealed in a duplicature of the mantle. 



Their shells are generally transversely striated, and decorated 

 with beautiful colours. 



Some of them are oval and thick. 



Others are oblong and strongly compressed. 



Some again are lenticular, where, instead of a plica, there is fre- 

 quently nothing but a slight deviation of the transverse striae ||. 



We might separate certain oblong species which have no lateral 



* Venus islandica, Chemn., VI, xxxii, 342, Encyc. pi. 301, f . 1 ; a large fossil 

 species is found in the hills of Siennois and nearDax, ofBourdeaux. 



t The Egeria, Roiss., or Galathaa, Brug., Encyc. 249, and Lam., Ann. du Mus., 

 V, xxviii, and Venus hermaphrodifa, Chemn., VI, xxxi, 327 — 329.' or Venus sub - 

 viridis, Gm. 



X Venus fiinbriata, Chemn., VII, 43, 448. 



§ See Deshayes, Coq. Fobs, des Eavir. de Paris, I. xiv ; Brongn., Mem. sur le 

 Vicentur. 



II These are the three divisions of Gmelin, but we must abstract from his genus 

 Tellina: 1st. Tell. Knorrii, which is a polished Capsa ; 2d. Tell, incequivalvis, viXuch 

 is the genus Pandora; .id. Tell, cornea; T. lacusiris ; T. aninica; T. JIuminalis ; 

 T.Jfuniinea ; T. fluvial His, which are Cytlades or Cyrense. 



