XXXll 



Sfrephohasis, Euryccdon, Goniohasis, Schizostoma, 

 3Ieseschiza, Anculosa. 



We thus proceed from a long canaliculate aper- 

 ture to one in which the aperture is entire, we also 

 commence Avith the largest and close with the small- 

 est sjDCcies. Pachychellus is not included in the 

 above, because it represents an extra-limital group, 

 and will probably be found to belong to another 

 family or subfamily. The same may be said of 

 Hemisinus and Pahidomtis. 



With regard to nomenclature, we will examine — 



1. lo, Lea. — We find this genus universally rec- 

 ognized European authors, however, do not seem 

 to understand its true limits, and include species of 

 Lithasia. 



2. PJeiirocera, Raf — Noth withstanding Mr. Lea's 

 assertion that Swainson's figure of Ceri^jhasia sulcata 

 does not represent a species of this genus, nor his 

 description correspond to it, I believe that Ceripha- 

 sia was certainly intended for that group of Tn/jxm- 

 ostomoid shells represented by canalicidata, Say, and 

 that the figure represents some such shell as 7\ 

 morlfornie, Lea. Gray, also, in 1847, proposed 

 Telescopella for Melania imdidata, Say, which belongs 

 to the same group. 



Thus, Mr. Lea's Trypanosto'nia is unquestionaoly 

 a synonyme. 



Pleurocera, Rafinesque, is the same shell, and 

 having priority over all the other names, I adopt it 

 without hesitation. 



Strepoma, Raf, manuscript, api^lies to the same 

 genus, and Oxytrema, Raf (Jour, de Physique) may 

 be intended for some immature form of canaUcuIata, 

 or its allies, which possesses the sharp-pointed aper- 

 ture described, — as lo variahilis, Lea, for instance. 



Messrs. Adams adopt Cerlphasia, but they sepa- 

 rate certain species, reticulate, or nodulosely carinate 

 in the middle, to form their genus Elimia. Their 

 Megara, also, consists of species of this genus. 



