OF CONCIIOLOGT. 1 13 



obvious external (bj no means generic) cliaracters, for facility 

 in their determination. He described a larare number of 

 species under the following divisions : — ■ 



" 1. Smooth. 4. Sulcate. 7. Granulate. 



2. I'licate. 5. Striate. 8. Cancellate. 



3. Carinate. 6. Tuberculate. 9. Spinose." 



Perhaps this division of the species suggested to Messrs. 

 Adams the genera which they have adopted in their classifica- 

 tion. 



In Philos. Trans., iv., p. 122, Mr. Lea proposed to institute 

 a new genus, /o, for the Fusns Jltivialis, o^ Say. His descrip- 

 tion is, " lo. — Shell fusiform ; base canaliculate ; spire elevated ; 

 columella smooth and concave." 



In his description ot Melania excisa, and Anculosa incisa, 

 published in Philos. Proc, ii, p., 242, Dec. 1842, Mr. Lea sug- 

 gested the name Schizostoma for those species having a 

 pleurotomose sutural slit in the outer lip. The genus thus 

 proposed, and which bears the same relation to Goniohasis as 

 Schazickeila does to Helicina, was some time afterwards cha- 

 racterized by Mr. Shuttleworth, from independent observa- 

 tion, under the name of Oyrotoma. 



In Philos. Proc. Aug. 1845, and in the Transactions, x.p. 67, 

 1853, Mr. Lea published the following description of his 

 genus : — 



"Schizostoma Lea. Shell conical or fusiform. Lip fis- 

 sured above. Aperture ovate, columella smooth, incurved. 

 Operculum. — 



"No operculum has come under my notice; but I can scarcely 

 doubt that it will bo found to be horny, and to resemble, in 

 other respects, that of Melania^ 



Subsequently (vol. x., p. 295,) Mr. Lea says, "When I pro- 

 posed the name of Scldzostoma for a genus of Mdaniana with a 

 cut at the superior portion of the aperture, I was not aware 

 that M. Bronn had already used that name for a fossil genus. 

 I now propose to substitute ScMzocheilus. " 



In the Proceedings of the Academy of Natural Sciences of 

 Philadelphia, 1860, p. 63, Mr. John G. Anthony makes some 

 lengthy remarks on this genus, as follows : — 



" Oyrotoma. As some confusion exists regarding the name 

 of this genus, the following notes are given: — 



"The genus 3Ielatoma was established by Swainson, and 

 first given to the world in 1840, in his ' Treatise on Shells 

 and Shell Fishes,' published in London, founded, as he says 

 (p. 202,) 'upon a remarkable Ohio shell sent him many years 

 before by his old friend Prof Rafinesque." ' It has,' he 

 remarks, ' the general form of a Pleurotoma and of a Mela- 



