them up, notwithstanding all the time and care they have bestowed upon them, 

 in a manner so as to make great confusion. Mr. Swainson, in his " Treatise on 

 Malacology," proposed a subgenus of Melania under the name of Ceriphasia, 

 and gives a figure, page 204, (C. sulcata,) stating it came from Ohio. It is 

 evident, on looking on this figure, that it does not represent any Ohio species, 

 neither in the aperture nor in the revolving ribs. Dr. Gray and the Messrs. 

 Adams* adopt the genus, and the latter give a figure (pi. 31, fig. 6) of canali- 

 culata, Say, as the type, which I do not think answers to the description or 

 figure of Mr. Swainson. Dr. Gray, in his excellent " List of the genera of Re- 

 cent Mollusca," in the Proceedings of the Zoological Society, expresses a doubt 

 whether his Telescopella may not be the same with Ceriphasia. Mr. Reeve, in 

 his beautiful work, " Conchologia Iconica," mixes may of our species in a man- 

 ner that does not admit of their being separated into groups ; and Dr. Cheau 

 (" Manuel de Concbyliologie") groups together some very incongruously. 

 Many of our groups are emphatically American, and the divisions made by our 

 zoologists have not had the attention they deserve from European writers. 

 Thus, neither Dr. Gray, Mr. Reeve, nor the Messrs. Adams adopt Prof. Halde- 

 man's genus Lithasia, established so long since, and which is an easily recog- 

 nized group. Mr. Reeve puts the various species of that group into my genus 

 lo to which they certainly do not belong, and Dr. Chenu puts part of them 

 there. The genus Amnkola, long since proposed by Gould and Haldeman, for 

 a very natural group of small shells, divided from Paludina, is not recognized 

 by Chenu or Reeve. 



In a future paper I propose to define the groups into which our Melanidas 

 seem naturally to divide themselves, adopting the well recognized genera 

 Vhich have been established. 



Trtpanostoma dux. — Testa carinata, pyramidata, crassa, rufo-fuscescente ; 

 spir& valde elevata ; suturis paulisper impressis ; anfractibus instar novenis, 

 planulatis ; apertura subgrandi, rhombica, intus pallido salmonia ; labro 

 acuto, sinuoso; columella incrassata, et valde contorta. 



Bab. — Tennessee River, W. Spillman, M. D. Fox River, Illinois, J. Sampson. 

 Oostenanla, Rev. G. White. Tuscumbia, B. Pybas. 



Trtpanostoma Thortonh. — Testa carinata, pyramidata, subcrassa, cornea 



* Messrs. Adams for the type of subgenus Juga give Buddii, Say. I am not aware 

 that Mr, Say described any Melanian under that name; and in Megara they give alveare, 

 Con. and basalis, Lea, as types, while they certainly belong to very different groups, 

 having very differently formed apertures. 



* 



