XIX 



Passing to American authors, we find Mr. Say was 

 the first to eUminate a native genus from the genus 

 Melania. In his description of Melanki prcerosa, he 

 says, " This shell does not seem to correspond with 

 the genus to which I have for the present referred 

 it ; and, owing to the configuration of the base of 

 the columella, if it is not a Melanopsis, it is probable 

 its station will be between the genera Melania and 

 Afjathlna. I propose for it the generic name of 

 Anculosa. 



He also remarks, in his subsequent description of 

 M. sifhglohosa, '• It is a second species of my pro- 

 posed genus Anculotus'' 



Mr. Say never described his genus ; but the above 

 citation and description of two species, both of which 

 are well known, and Avhose identity with his descrip- 

 tions has never been questioned, entitle his generic 

 name to be received as authority. 



Rjifinesque published the following genera, which 

 have been referred to Strejyomatidce : — 



" Pleurocera, Raf. (Jour, de Phys. Bruxelles, vol. Ixxxviii, 

 p. 423, 1819). Shell spiral, oval, or pyramidal, of numerous 

 convex volutions. Aperture obliquely oblong, the base pro- 

 longed and twisted, sharp above. Outer lip thin, the inner lip 

 appressed, twisted, without umbilicus. Animal with a mem- 

 branaceous operculum. 



"Head proboscidiform, inserted on the back ; tentacles two, 

 lateral, subulate, sharp, with eyes at their exterior bases. 



"Family of Neritacea. Species numerous, of which I have 

 already twelve, all fluviatile, from rivers and creeks, as well as 

 the following genera."* 



♦Rafinesque previouslj^ described Pleurocera in a short paper pub- 

 lished in the American Monthly Maj^azine and Critical Review, iii, p. 

 354, 1818 (Binney & Tryon's edit, of Kalinesque, p. 22), as follows: — 



" Shell variable oboval or conical, mouth diagonal crookeil. rhom- 

 boidal, obtuse and nearly reflexed at the base, acute above the con- 

 nection, lip and columella llexuose entire. Animal with an opt'roulum 

 membranaceous, head separated from the mantle inserted above it, 

 elongated, one tentaculum on each side at its base, subulate acute, 

 eyes lateral exterior at the base of the tentacula." 



This description was doubtless intended for all the elongate species 

 of ]\Ielanians from the Ohio River then known to him, but he after- 

 wards amended it as above. 



In his '> Enumeration and Account" (Binney & Tryon, p. G7), Rafl- 

 nesque describes several species of Pieurocera, and remarks, '' My G. 



