BIVALVIA- 35 



VULSELLA. Humphries, 1797. 



Tellina (sp.) Rumph., 1705. 



Pinna (sp.) Linn. 1758. 



Mya (sp.) Id. 



Bapiiia (sp.) Gevers, 1787. 



Ostrea (sp.) Bniff., 1780. WOrb., 1850. 



Vulsella. Lamk., 1799. 



Dalacia? Gray, 1825. 



Reniella. Swains., 1840. 



Gen. Char. Shell somewhat irregular, elongated, compressed, inequivalved, free ; 

 hinge with connexus external or ligamentous ; umbones straight, remote, earless ; one 

 muscular impression in each valve, subcentral. 



This is a genus containing but few species, either in the recent state or as fossil. 

 Six recent species have been described, and these are confined to the Oriental seas. 



Lamarck had placed this genus close to Ostrea, to which in many of its characters it 

 bears a great resemblance ; it is truly monomyarian, and the connexus is situated as in the 

 oyster, between divergent beaks upon an inclined plane, opening the valves by contraction. 

 Cuvier removed it from that position to one in proximity with Malleus ; and some authors 

 still consider it only as a section of, or sub-genus to, Avicula. Judging from the shell alone, in 

 the absence of a knowledge of the animal, the differences are too conspicuous to be included 

 in that genus, and it appears to me entitled to claim an isolation equal to many other 

 generally admitted genera. 



Shells bearing the above generic characters have been found in the Chalk. 



1. Vulsella deperdita? Lamarck. Tab. IX, fig. 2, a — c. 



Vulsella deperdita. Lam. Hist, des An. sans Vert., t. vi, p. 222, No. 7 • 



— — Defrance. Diet, des Sc. Nat., art. Vulsella. 



— — Desk. Coq. Foss. des Env. de Par., p. 374, pi. 65, figs. 4—6". 



— — Id. An. sans Vert, du Bass, de Par., t. 2, p. 51, 1860. 



— — ? Grateloup. Cat. des An. Foss. des Env. de Bord., p. 59, 1838. 



— — Morris. Cat. of Brit. Foss., p. 182. 

 Ostrea deperdita. D'Orb. Prod, de Palseont., p. 394, 1850. 



Spec. Char. Testa ovato-oblongd, angusfd, incequwahd, sub-lingulatd, sublcevigatd, 



superne tumidiore, apice retusd ; fossuld cardinali magna, oblique incumbente, laterali, 



basi jprominuld ; area cardinali sinuato ; impressione musculari sub-laterali, elongafo- 

 ovatd. 



