IW 



preoccupied ii. tines. Suitor objected t.. flu- adoption of Hall's name, !> 

 inappropriate aii<I conveyed "an entirely erroneou- view of tlit- all'mities." This of 

 itself certainly would not be sufficient to invaliilate the name, yet some weight 

 attaches to it when considered in connection with other defects. Salter justly 

 observe- that the chief characters of the genus reside in the hinge and teeth, 

 which are neither figured nor described by him (Hall), casts only of the interior and 

 external surface having been given in the plates of his excellent work, nor was the 

 external ligament observed." This is all strictly true and, what is more, it is scarcely 

 to be doubted that if Hall had observed the nuculoid character of the hinge he would 

 not have proposed Tfllinonii/ii. He would have placed the species under Nucula or 

 possibly /.</'"'/'>"'". that being the arrangement adopted by him in all cases where 

 he did see the ctenodontoid hinge. Nor can we doubt that Ctenodontn was acceptably 

 -ibed at least five years before Tellinomya, Hall, was redefined in accordance 

 with the true character of the shells upon which the genus .was founded originally. 

 finally, the original description of Tellinomi/u was so totally at variance with the 

 that Salter could not for a moment be blamed for failing to recognize the 

 identity of /'. mi.tnfn and the >hell which he proposed to call Clenodontu. 



Taking all these defects of 7V/// Homy/ into consideration. I do not see how we 

 can do otherwise than adopt CtenodonUt in preference to Hall's name. Had Tellin- 

 ' not been preoccupied I would have suggested another solution of the difficulty, 

 namely, to subdivide the genus so that both names might be used, at least provision- 

 ally. Tellinomi/ii for the typical group of species and Cten<xlonta for the higher and 

 round or subtriangular forms like C. agtartiformis Salter. But being preoccupied, 

 there is no room for Tellinomya in this connection. 



Taken as a whole, the genus Cltnodontn is a remarkably complex group of 

 species. This may perhaps be accounted for by the great number of the recog- 

 ni/aiile forms, yet it is more likely the result of too great an expansion of the 

 generic limits. Indeed, the variety of characters exhibited in the genus as now 

 accepted is so great that it is difficult to draw up a satisfactory description without 

 becoming unusually circumstantial. Thus, there are elongate shells and others in 

 which the length is exceeded by the bight. In many the outline is elliptical, in some 

 Mibrhomboidal. in others rounded and in a few subtriangular. In some the umbones ' 

 are compratively large and full, in others very small, and the beaks may l>e turned 

 either forward or backward. Internally the struct me i- equally diverse. The hinge 

 plate may be narrow or broad, nearly straight or bent rectangularly, and with out- 

 wardly or inwardly bent denticles. The latter, though always smallest near the 

 beaks, may form a continuous series from one end of the hinge to the other, or the 

 continuity of the series may be interrupted beneath the beak. This interrupt 



