NEW MELANIDiE OF THE UNITED STATES. 269 



aperture, the type of which may be considered to be Mr. Say's Melania cancdiculata, a 

 very common and well known species from the basin of the Ohio River. It will include a 

 number of large species ; indeed, nearly all of the large and ponderous species of the 

 United States. Many new ones will be found in this paper. Objections may be raised 

 against now increasing the number of genera without the aid of the examination of the 

 soft parts. But there is no validity in this objection, from the fact that, in the present 

 condition of the science of Malacology, we are becoming acquainted with a vast 

 number of new and interesting forms, without the hope at present of seeing the organic 

 portion of the animals. These may at some future time, and no doubt will, be ex- 

 amined and carefully described by zoologists who may dwell near the waters where 

 these numerous and highly developed species reside. Until this takes place we can 

 only group them upon the characters which are presented by their outward hard por- 

 tions, which are accessible to us now. 



In proposing this new genus I am aware that European Zoologists have made many 

 genera and subgenera in this Family, but none have made groups of our numerous 

 species by which they can be properly divided. They have mixed them up, with 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 at this figure that it does not represent any Ohio 

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

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

 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 Recent Mollusca," in the 

 Proc. Zool. Soc, expresses a doubt whether his Telescopella may not be the same with 

 Ceriphasia. Mr. Reeve, in his beautiful work, " Conchologia Iconica," mixes up many 

 of our species in a manner that does not admit of their being separated into 

 groups, and Dr. Chenu ("Manuel de Conchyliologie") groups many 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. Haldeman's genus 

 Lithasia, established so long since, and which is an easily recognised group. Mr. 

 Reeve puts them into my genus Io, to which they certainly do not belong, and Dr. 

 Chenu puts part of them there. The genus Amnicola, long since proposed by Gould 

 and Haldeman for a very natural group of small shells divided from Paludina, is not 

 recognised by Chenu or Reeve. 



I have elsewhere proposed to define the groups into which our Melanidre seem 



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