SECTION VII. 



H3 



of a Bivalve. They feem to be of two 

 kinds, and are more irregular than that 

 Shell, and, inftead of being falcated length- 

 wife, are circularly wrought, or in a tranf- 

 verle manner, with very high irregular 

 ridges, not thickly, but rather thinly fet. 

 The Shells are very thick. One fort is high, 

 or xropped, the other is broad or flattidi. 

 The infide is quite fmooth, the edges turn 

 outwards, and, under the beak, or that 

 part which anfwers to the hinge in Bi- 

 valves, they ftretch out (all towards the 

 fame fide) into a broad flat ledge, the per- 

 pendicular fide of which, is curioufly w^ork- 

 ed with ftreight and parallel furrows, like 

 td the hinge of a Multarticulate Bivalve. 

 On the very top or beak part, it has a 

 large, wide, roundifh opening, like a frac- 

 ture, which, from its remarkable thinnefs, 

 makes it difficult to determine, whether 

 It be a natural perforation or an accidental 

 fradure, though, by its regular edge, and 

 being quite alike in all the four fpecimens, 

 pne would incline in favour of the former. 



Family 



