PULVINITES. 



Befr, 



TESTA bivalvis, insequivalvis, inaequilateralis, 

 compressa, tenuis, latere antico paululum 

 hiante; valva altera plan ata, altera coneavius- 

 cula; eardine lineari, brevi, posticali, sulcis 

 perpendieularibus diviso ; impresslonibus mus- 

 cularibus duabus, parvis, infra cardinem positis, 

 inferioresubcentrali, majore;ligamento interne, 

 sulcis cardinalibus affixo? 



■ 



Named from its resemblance to a little cushion, by Defrance. 

 Being only known in a fossil state, it is difficult to assign 

 to it its proper characters or to distinguish it from Perna, 

 Crenatula and Inoceramus, to each of which it bears 

 some resemblance. This curious fossil was discovered in 

 Normandy by our friend De (lerville, in the bed of Bacu- 

 lite Limestone of Fresville near Valognes. It seems proper 

 to give a representation of it here, in order to draw the 

 attention of Naturalists, and rather to gain information, 

 considering that at present we are so imperfectly acquainted 

 with it. 



Pulvinites is an inequivalve, and very inequilateral 

 bivalve, which is compressed and thin; and the anterior side 

 is somewhat gaping; one valve is nearly flat, the other 

 slightly concave ; the hinge is linear, short, and placed 

 closely behind the umbones ; and it is divided by perpen- 

 dicular grooves. The muscular impressions are two, small, 

 one of them very small and placed immediately below the 

 hinge, the other placed lower down, is larger and nearly 

 central. Not having seen the recent shell we can only 

 suppose the ligament to be internal, and to be attached to 

 the perpendicular grooves of the hinge. For the same 

 reason we are not aware whether or not the shell be affixed 

 by a byssus. 



