106 CONCHIFERA. DIMYAIBA. 



Gen. 37. PkTRicoLA, Lam. 



Shell bivalve, subtrigonal, transverse, inequilateral, with the pos- 

 terior side rounded, the anterior attenuated, and slightly gap- 

 ing ; hinge with two teeth in each valve, or in one only. 



P. semi-lamellata. Shell slender, white, trigonal, with distant trans- 

 verse furrows, the upper ones lamellated ; interstices longitudi- 

 nally striated ; two teeth in one valve and one in the other. In- 

 habits rocks near Rochelle. Lam. v. 504. 



P. rocellaria, Lam. Shell ovate-trigonal, with longitudinal rugose 

 furrows, and distant transverse striae ; two teeth in one valve and 

 an obsolete one in the other. Inhabits stones near Rochelle. 

 Lam. v. 504. 



P. linguatula, Lam. Shell small, transversely oblong ; the poste- 

 rior side very short, the anterior elongated, subtruncated. In- 

 habits coasts of New Holland Lam. v. 505. 



Fossil species of this genus have been found in Italy. 



Gen. 38. SAXICAVA, Lam. Mytilus, Lin. 

 Shell bivalve, transverse, inequilateral, gaping anteriorly at the 

 upper margin ; hinge almost without teeth; ligament exterior. 



S. pholadis, Lam. Shell oblong, rough, transversely rugose, obtuse 

 posteriorly. Inhabits Northern seas, in rocks and stones. 

 Lam. v. 502. 



S. Australis, Lam. Shell ovate, turgid, transversely striated, the 

 anterior side with oblique subangulated ribs. Inhabits seas of 

 New Holland. Lam. v. 502. 



FAMILY III. CORBULACEA. 

 Shell inequtvalve ; ligament interior. 



The shells of this family are of medium size or small. One of the beaks is al- 

 ways more protuberant than the other. 



Gen. 39. PANDORA, Lam. Tellina, Lin. 

 Shell regular, inequivalve, inequilateral, transversely oblong, 

 with the upper valve flattened, and the under one convex ; 

 two oblong primary, diverging, and unequal teeth in the up- 

 ver valve, and two oblong grooves in the other valve; li- 

 gament interior. 



P. rostrata, Lam. (T. incequivalvis, Lin.) Shell oblong, white, 

 glossy, beaked anteriorly, and arcuated on the cartilage slope ; 

 hinge somewhat lateral. ^ inch long by 1 broad. Inhabits Eu- 

 ropean seas. B Wood's Conch, pi. 47, fig. 2, 3, 4. 



Gen. 40. CORBULA, Lam. Mya y Mont. 

 Shell regular, inequivalve, inequilateral ; a single primary tooth 



in each valve, conical, bent, ascending, and a hollow at its 



side ; no lateral teeth ; ligament interior. 

 C. Auslrale, Lam. Shell ovate, widely inequilateral ; margin slight- 



