MOLLUSCA. 741 



Remarks. Tuomey's original description of this species is as 

 follows: "Shell top-shaped; spire depressed, almost flat; body 

 whorl angular, terminating suddenly in a canal." In the absence 

 of any illustration it is exceedingly difficult to make any identi- 

 fication from such a meagre definition as this, and more especially 

 when the specimens to be identified are internal casts and the 

 definition a description of the shell itself. Furthermore the 

 whereabouts of the type specimen is not known. The internal 

 casts which Whitfield referred here cannot possibly belong here, 

 however, because the body volution is not in the least angular, 

 although the spire is nearly flat. Judging from the original de- 

 scription, the shell would seem to come very close to the shell 

 described from Tippah County, Miss., by Conrad as P. perlata, 

 the type of the genus Pyropsis ; indeed Conrad himself suggested 

 the identity of the two forms, 1 and Gabb has considered them as 

 identical without any question. 2 Gabb came to this conclusion 

 through a study of numerous specimens of these shells from 

 Mississippi and Alabama, among which was the type of P. per- 

 lata, and it is reasonable to suppose that he was correct in his 

 conclusion, and his interpretation of the two species will be fol- 

 lowed here. 



In Whitfield's monograph both the species, P. perlata and P. 

 richardsoni have been given a place, the specimens upon which 

 both identifications have been made being internal casts. A crit- 

 ical study of both the forms recognized by Whitfield leads to 

 the conclusion that neither of them are really representatives of 

 the southern species under consideration. Indeed, true repre- 

 sentatives of P. richardsoni seem to be exceedingly rare in the 

 New Jersey faunas, a single individual from" the Merchantville 

 clay-marl near Matawan having been observed, and a second 

 specimen from the Navesink marl. The former is a very 

 incomplete internal cast with a portion of the impres- 

 sion of the exterior. A plaster cast taken from this natural 

 mould shows the external features of the shell, so far as they 

 go, of essentially the same character as those of the type of P. 



1 Am. Jour. Conch., vol. 4, p. 248. 



2 Proc. Acad. Nat. Sci. Phil. (1876), p. 284. 



