58 



tations hcon })iil)lishc(\ ;* the (jlenus lia«, however, been 

 uniformly acimittcd as distinct. Its great resemblance 

 to Crenatula, has sometimes induced me to think that it 

 ought to be joined with that Genus ; but a close com- 

 ])arison of the hinges in many specimens of different 

 species, all of which are wholly destitute of the spoon- 

 like processes characteristic of Crenatula, joined with a 

 consideration of its prominent beaks and gibbose form, 

 has confirmed my Father's opinion, and proved the ac- 

 curacy of his judgment. Brongniart not knowing which 

 species was the type of this Genus, and thinking the very 

 prominent, unequal beaks of the two species belonging 

 to the second section, a sufficient reason to distinguish 

 them from it, has placed it in a newly formed Genus, 

 which he has called Catillus ; but he probably v/as not 

 sufficiently acquainted with the hinges of the species he 

 still retains as Inocerami, to perceive their resemblance 

 to the type. As to the Genus Perna, its species are of 

 a much more foliated structure, and have a considerable 

 sinus for the passage of the byssus ; it is, therefore, 

 readily distinguished. 



The name Inoceramus, from *u (fibra) and xepujuoi 

 (testa) is justly objected to by scholars, as an improperly 

 formed word, and not expressive of " fibrous shell'* 

 which it was intended to signify ; it therefore ought to 

 be changed, but it has been in use so long, that it has 

 become general ; and, if I were even inclined to act the 

 part of an innovator, to do so would, 1 think, only be 

 adding to the confusion already existing in consequence^ 

 of Byongniart's naming the type of the Genus, Catillus, 

 a name not applicable to the whole of the species. 



This Genus occurs in many strata from the Mountain 

 Limestone to the Chalk. 



*Sec Mr. MantiH's observation upon the knowledge of the structure 

 of this shell, page 212. and compare it with the paper in Liun. Trans. 

 Vol. XIJI. page 455, Sic. 



