380 PROCEEDINGS OF THE ACADEMY OF [PaRT II 



RISSOIDAE. 



Not many members of this family are in the collection. Gabb 

 had no luck with his classification of the few obtained, the species 

 of Rissoina being referred to four genera. The new genus lopsis 

 was based upon the young stage of a Rissoina. 



The Rissoinas of the Santo Domingan Miocene seem to have 

 changed very little since that time, all of those known being iden- 

 tical with, or very closely related to, modern species of the same region. 



The genus CrepitaceUa Guppy, 1867 (-\-Dolophanes Gabb, 1873) 

 is closely related to Rissoina, but may be held distinct by the simple 

 lip, which is sharp, without any trace of the external varix which 

 strengthens the lip of Rissoina. Otherwise it has essentially the 

 structure of Rissoina. 



CrepitaceUa cepula (Guppy) Plate XXXIV, figs. 12. 13. 



Mdanopsis capula Guppy,-'^ Quart. Journ. Geol.Soc.,xxii, 1866, p. 580, pi. 26, 



fig. 14. (M ela no psis cepula on p. 590). 

 CrepitaceUa cepula Guppy, Geol. Mag. iv, 1867, p. 500,; Quart. Journ. Geol. 



Soc, xxxii, 1876, p. 524. 

 Dclophanes melanoides Gabb, Proc. A. N. S. Phila., 1872, (1873), p. 273, pi. 



11, fig. 7; Trans. Amer. Philos. Soc, xv, p. 235. 

 Pleurotoma (Mangilia) columbella Dall, Bull. M. C. Z. ix, 1881, p. 60. 

 Plcurotoma {melanoides var.?j columbella Dall., Rep. ''Blake" Gastrop. 1889. 



p. 271. 

 Dolophanes {melanoides Gabb, var.) gabbi, Dall, Rep. "Blake" Gastrop. 



1889, p. 270, pi. 29, fig. 7. 



As the affinities of this snail have been variously estimated by 

 the conchologists who have considered it, some statement of the 

 changes of opinion may not be out of place. Melanopsis capula 

 (cepula) was described from a formation thought to be Upper Mio- 

 cene, at Cumana, Venezuela. Mr Guppy says: 



"I do not. know of any form resembling this species, which was 

 probably not a freshwater shell. It may possibly have been an estu- 

 arine form. It reminds one of a shortened and widened Eulima, or 

 even a SiyJifer." 



In forming the new genus CrepitaceUa for the species, in 1867, 

 Mr. Guppy notes: 



''The true position of this shell is probably in the neighborhood 

 of the family Buccinidae, in which I have provisionally placed it. Its 

 nearest relation known to me is Cyllene puIcheUa Adams." 



In 1876, Guppy again referred to CrepitaceUa cepula, placing Dolo- 

 phanes melanoides Gabb in the synonymy. 



"^^ The name capida was no doubt a typographical error, as in all subsequent 

 references Mr. Guppy called the species cepula (a diminutive of cepa). The syn- 

 onjTny was worked out by Mr. C. W. Johnson. 



