XXV 



"On the 14th of December, 1842, Mr. Lea read a paper 

 before the American Philosophical Society, in which he de- 

 scribes Melania excisa and Ancnlosa mcisa. In his remarks 

 upon these species he alludes to the pleurotomose cut in the 

 superior part of the upper lip, and at the time suggests 

 the necessity, in consequence of this character, to construct a 

 new genus, which he proposed to call ' Schizostoma.' Mr. Lea, 

 finding his name ' Schizostoma' preoccupied in palgeontolog}', 

 changed it to '' ScJuzochilus' (March 5, 1851, Obs., v, p. 51). 

 In a paper read May 2, 1845, Mr. Lea, in a foot-note to p. 93, 

 first indicates the generic characters of Schizosto^na, as follows ; 

 'Testa vel conica vel fusiformis ; labrum superne fissura ; 

 aperture ovata ; columella laivis, incurva,' — and describes six 

 additional species. 



"In the above concise definition of the genus, it will at 

 ouce be noted that the fissure at the upper part of the outer 

 lip is, after all, the essential character ; and Mr. Lea himself 

 seems to be aware of this, since, of the six species then de- 

 scribed, he states the aperture to be elliptical in five cases and 

 rhomboidal in the other, although his generic character is 

 'aperture ovate.' Indeed, in the species described by him, but 

 a single one has the aperture ovate, and that one is described 

 as an Anculosa. 



"It may be doubted whether Mr. Lea's first name will not 

 eventually prevail, since, before he published Schizostoma, 

 Bronn's genus of the same name (Lethea Geogn., i, 95, 1835- 

 37) had 'been called a synonyme oi Bifrontkt {Omalaxis) of 

 Deshaves. (Vide Desh. in Lam., ix, p. 104.) Indeed, II. & 

 A. Adams (Gen. Rec. Moll., i, 305) do not appear correct in 

 giving preference to G>/rotoma over Schizostoma, Lea, on ac- 

 count of Schizostoma, Broun, since (on p. 244) the latter is 

 placed in the synonymy of Omalaxis. 



"Another generic name Schizostoma is quoted in Hermann- 

 son's Index. I have not obtained access to the work contain- 

 ing this description ; but its date is said to be anterior to Mr. 

 Lea's description. 



"Mr. Lea's second name, Scliizochilus^ had been previously 

 used in Coleoptera, but withdrawn after Mr. Lea's description 

 was published. 



"Mr. Shuttleworth, in July, 1845 (Mittheilungcn der Na- 

 turforschenden Gesellschaft in Bern, p. 88), gives another 

 description of the genus under the name of Gyrotonia, founded 

 on two species from the Coosa River, descriptions of which 

 are also given. 



" The generic name of IMr. Shuttleworth has been adopted in 

 H.& A.Adams' Genera of Recent Mollusca (i,p.305, Fel)., 1.S54). 



"Dr. Gray also (Guide to Mollusca, i, p. 103, 1857) adopts 

 Shuttleworth's name. 



