GERVILLIA. 



TESTA oblonga, subsequivalvis, inaequilateralis, 

 valde obliqua, cardine longiusculo, linean, 

 rectiusculo, fossulis dentibusque pliirimis 

 irregularibus, subtransversalibus, infra niar- 

 ginem dorsalem positis. Testa, nisi in statu 

 tbssili, omnino ignota, quare ligamentum bys- 

 siisque non extant. 



As far as we can judge from the fossil remains of a shell 

 alone this may be regarded as an intermediate Genus, and 

 might be arranged between Avivula and Perna; in its 

 general form and external appearance it resembles the 

 former, while its hinge is somewhat like that of the latter, 

 though sufficiently different from it to enable us to point 

 out without difficulty the peculiarities by which it may at 

 once be known. 



This is one of the few Genera of shells which appears 

 to be quite extinct, although many species have occurred 

 at various geological periods from the Lias upward, to the 

 Baculite Limestone of Normandy, in which latter bed that 

 species was first discovered, upon which the Genus has 

 been established by our friend De Gerville, after whom 

 Naturalists have named it. 



Shell oblong, nearly equi valve, very inequilateral 

 and oblique \ hinge line rather long, linear, nearly straight, 

 with many irregular, rather transverse little pits and 

 ' teeth placed below the dorsal edge ; the shell not being 

 known in a recent state we are unable to describe the 

 ligament, or to state whether or not it is adherent by a 

 byssus, though there is good reason for presuming that it 

 is. We judge it to have been marine from its associates. 



