BIVALVIA. 35 
VULSELLA. Humphries, 1797. 
TELLINA (sp.) Rumph., 1705. 
Pinna (sp.) Linn. 1758. 
Mya (sp.) ih = 
Baputa (sp.) Gevers, 1787. 
Osrrea (sp.) Brug., 1789. D’ Orb., 1850. 
VuLSELLA. Lamk., 1799. 
Datacta? Gray, 1825. 
RENIELLA. Swains., 1840. 
Gen. Char. Shell somewhat irregular, elongated, compressed, inequivalved, {vce ; 
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 J/a//ews ; and some authors 
still consider it only as a section of, or sub-genus to, dvicu/a. 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. Vunsenta peperpira? Lamarck. Tab. IX, fig. 2, a—e. 
VULSELLA DEPERDITA. Lam. Hist. des An. sans Vert., t. vi, p. 222, No. 7. 
— _ Defrance. Dict. des Sc. Nat., art. Vulsella. 
— Desh. Coq. Foss. des Envy. de Par., p. 374, pl. 65, figs. 4—6. 
— Td. An, sans Vert. du Bass. de Par., t. 2, p. 51, 1860. 
— ? Grateloup. Cat. des An. Foss. des Eny. de Bord., p. 59, 1838. 
— — Morris. Cat. of Brit. Foss., p. 182. 
OstrEA DEPERDITA. D’Orb. Prod. de Paleont., p. 394, 1850. 
Spec. Char. Testd ovato-oblongd, angustd, inequivalvd, sub-lingulatd, sublevigata, 
superne tumidiore, apice retusd ; fossuld cardinali magna, oblique incumbente, lateral, 
basi prominuld ; ared cardinali sinuato ; impressione musculart sub-laterali, elongato- 
- ovata. 
