225 



valve, with two oblong, unequal, and diverging hinge teeth, in the supe- 

 rior valve, and two oblong corresponding pits in the other valve : the 

 cartilage interior, and two muscular impressions. 



This shell is thin, and semi-transparent, the dorsal suture straight, pro- 

 longing and widening itself at one end. One valve is convex, and the 

 other flat. The inequality of the valves separates this shell from the 

 Tellens. Tellina inequivalvis, Linn, is referred to this genus, of which 

 no fossil shell has been mentioned. 



CXLIX. Corbula. A subtransverse, inequilateral, inequivalved bi- 

 valve, with rather prominent and incurvated beaks : a single conical re- 

 curved hinge-tooth in each valve ; the cartilage internal : two lateral 

 impressions. 



This is exceedingly distinct from every known genus. The beaks of 

 these shells are particularly tumid and curved inwards, and one of their 

 sides is much more lengthened and thin than the other. Lamarck refers 

 the shells Vol. x. Tab. 172, No. 1668 to 1671, in Chemnitz's work, to 

 this genus. He also describes eight fossil species found in the environs 

 of Paris : C. gallica, C. rugosa, C. striata, C. angulata, C. anatina, C. argen- 

 tea, and C. cancellata. 



C. gallica is the largest of these, and that in which the characters of 

 the genus are most decidedly shown : it is generally about an inch and a 

 half wide. M. Lamarck observes, of this shell, that it is transverse, 

 oval, tumid; and very singular, from the lower valve being smooth, and 

 having its hinge-tooth originate beneath the edge, and curve up towards 

 the beak; whilst, in the upper valve, longitudinal -striae are evident, 

 and the tooth proceeds from the edge of the valve, is compressed, and 

 stands up perpendicular. It is not, however, certain whether these may 

 not be valves of distinct species, since they havQ always been found sepa- 

 rated. 



Plate XVI. Fig. 2, represents the inside of the smooth valve of C. gal- 

 lica, in which may be perceived the hinge-tooth, approximating to the 

 beak. 



VOL. III. G G 



