214 PROCEEDINGS OF THE ACADEMY OF [1879. 



The description and figure of Fusus nanus as given by Lea in 

 his "Contributions," agree in all essential respects with the above. 

 No mention is made of the sinuated lines of growth peculiar to 

 the rieurotomae, which in our specimens are very distinct. 

 Although I have not had an oppprtunity to examine Mr. Lea's 

 specimens, it appears to me, nevertheless, highly probable that 

 his Fusus will prove to be a Pleurotoma. 



Pleurotoma denticula, P.aterot. PI. xiii., fig. 10. 



This species, which is one of the most widely diffused of all 

 fossil Pleurotomse, has to my knowledge not been hitherto de- 

 scribed as occurring in any American formation. The P. nodo- 

 carinata, Gabb (unfortunately very poorly figured), in the collec- 

 tions of the Academy belongs to this species. Specimens are to 

 be found also in the Claiborne accumulation of the American 

 Museum of Natural History, New York. 



MELANIA, Lam. 

 Melania Claibornensis, nob. PI. xiii., fig. 11. 



Shell elongated, turreted ; whorls eight, of which the first three 

 are smooth, and the rest furnished with longitudinal folds, those 

 on the bod} r -whorl terminating at about the middle; folds cut by 

 numerous deeply impressed revolving lines, giving a somewhat 

 imbricated appearance; mouth elongated, oval contracted above, 

 and expanding at the base; columella broad, flattened. 



Length .3 inch. 



Claiborne, Ala. 



This species, to which I have provisionally applied the specific 

 name of Claibornensis, is doubly interesting as being the only 

 essentially fresh-water gasteropod found in the Claiborne marine 

 formation and of being at the same time most intimately related 

 to a species found in the Paris basin, Melania mixta, Deshayes. 

 It agrees essentially with all the characters as given by Deshayes, 

 and on comparison with his specimens will in all probability 

 prove to be identical. 



RISSOINA, D'Orbigny. 

 Rissoina plicato-varicosa, nob. PI. xiii., fig. 12. 



Shell sub-turreted ; whorls about seven, convex, ornamented 

 with numerous longitudinal folds (on the body-whorl from 10 to 

 12), and disfigured by several prominent varices; revolving lines 



