Contributions to Paleontology. 



Ill 



It becomes necessary, in this connection, to notice the Genus 

 Spoxdylobolls of M'Coy, published in the Annals Xat. History, 

 2d series, Vol. viii. p. 408 : and in British Palasozoic Fossils, p. 

 255. 1855. 



The following is the description of that genus : 



GEXUS SPOXDYLOBOLUS (M'Coy). 



" Generic character. Suborbicular, slightly narrowed 

 " towards the iudistinct short hiuge-liue, nearly equivalve, 

 "flattened. Small valve with a slightly excentric apex ; 

 " beneath which, on the interior, the substance of the 

 "valve is thickened into a wide undefined boss. Oppo- 

 " site valve slightly longer, from the apex being perfectly 

 H marginal and slightly produced, chauneled by a narrow 

 "triangular groove below, the anterior end of which is 

 "flanked by two very prominent, thick, conical, shelly 

 "bosses representing hinge-teeth: substance of the valve 

 " thick, testaceous, not glossy, minutely fibrous, but not 

 " distinctly punctated under a lens of moderate power, 

 " except by the ends of these fibres." 



Whether the characters here given are such as will bear some 

 extension by the study of a larger number of species; and whether, 

 if somewhat extended, they may not include some of those forms 

 like Obolella, I shall not discuss at the present time. With the 

 exception that the apex of the small valve is described as slightly 

 excentric, the description corresponds more nearly than that of 

 Obolella with the shell before me. 



