XXVll 



correct in giving preference to Gyrotoma over ScMzostoma, 

 Lea,' «fec. Notwithstanding this, Mr. Antliony in this paper, 

 where he describes nine supposed new species of this genus, 

 adopts the generic name of Gyrotoma. It may be added here, 

 that Dr. Gray, in his Genera of Recent Mollusca^ gives Mela- 

 toma to Mr. Antliony, not to Swainson, while he does not 

 notice the name of Schizostoma. Mr. A. does not pretend to 

 claim it, of course, but adopts Gyrotoma, Mr. Shuttleworth's 

 name, proposed in 1845, which, being three 3'ears later, cannot 

 have precedence. 



" The genus Schizostoma seems to be capable of being divi- 

 ded into two natural groups in the form of the Jissura, the cut 

 in the lip. In one groui»this fissura is deep and direct, that 

 is, parallel with the suture or upper edge of the whorl ; in the 

 other it is not deep and is oblique to the suture." 



In the same Journal (April, 1862), was published 

 a new genus, with the following name, description 

 and remarks : — 



" Genus Tkypanostoma, Lea. 



" Shell conical ; aperture rhomboidal, subcanaliculate below. 

 Lip expanded. Columella smooth, twisted below. Operculum 

 corneous, commencing spiral. 



" The enormous number of species in the genus Melania has 

 made it very desirable to eliminate as mau}^ as possible, by 

 founding new genera, where well characterized groups can be 

 established. With this view I proposed, in the Proceedings 

 of the Academy, in April last, the genus StrepJiobasis. The 

 genus now proposed under the name of Trypanostoma, will 

 include all the well known Melania with an auger-shaped aper- 

 ture, the tj-pe of which may be considered to be Mr. Say's 

 Melania canaliculata, 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 increas- 

 ing 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 examined and carefully de- 

 scribed 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 portions which are 

 accessible to us now. 



