182 



rounded, the latter somewhat more obtusely so : basal margin 

 regularly rounded, without any undulation before: apex obtuse, 

 but little prominent : cardinal teeth two : fosset dilated fusiform, 

 abruptly very narrow at the beaks : lateral teeth none : posterior 

 muscular impression very slender, and elongated. 



This species is more transverse than usual in this genus ; it is 

 altogether destitute of lateral teeth, and the posterior muscular 

 impression is remarkably slender. It is superior in point of size to 

 either the orhiculatum or radiatum, nob., though proportionally 

 somewhat thinner. I obtained a specimen on the coast of Georgia 

 that is somewhat worn ; its color is whitish, a little tinged with 

 yellowish. PI. 28 ; middle figures. 



Amphidesma ^quale. — Specific character. Left valve with 

 remote grooves instead of lateral teeth. 



Amphidesma sequale, nobis. Jour. Acad. Nat. Sci., vol. 2, p. 

 307. 



Obs. — This is allied to A. tenue and Boy sit, Montagu, of the coast 

 of England, of which, however, I have not any good description or 

 specimen to compare, and it may possibly prove to be the same with 

 one of these, when compaiison shall be made. 



Since my quoted description was given, many specimens have 

 been found on the coast of Charleston, for which I am indebted to 

 the late Mr. Stephen Elliott. 



It belongs to the genus Abra of Leach. PI. 28 ; four exterior 

 figures. 



Fusus. — Shell imi valve, spiral, fusiform, canaliculated at base, 

 covered with an epidermis, and destitute of varices ; spire elevated ', 

 aperture oval ; columella simple ; labrum on" its edge simple ; oper- 

 culum horny, subconcentric. 



Obs. — This genus was separated from the Linnsean Murex by 

 Bruguieres, who, however, included Pyrula, Fasciolaria, Fidgur, 

 and Pleurotoma, which have since been withdrawn from it by La- 

 marck and Montfort. The latter author distinguished another 

 genus by the name of Latirus, for the umbilicated species. Not- 

 withstanding these improvements, it is still acknowledged to be 

 an artificial assemblage, and more divisions must therefore be made. 

 Lamarck places the genus in his fjimily of Canalifires ; from all 

 the genera of which it is distinguished by very obvious characters, 

 excepting Pynda, which, however, consists of thin, more or less 



