8 



THE NAUTILUS. 



Alabama system. Compared with that, it is smaller, narrower, 

 with a more obtuse apex, the posterior slope is straight and 

 not convex and the lateral slopes less oblique than in that 

 species. The tinted apical area seems smaller than in the other 

 species of the genus and is frequently lost entirely from erosion. 

 The radula has not yet been examined. 



Rhodacmea elatior (Anthony). 



Ancylus elatior Anthony, Ann. N. Y. Lye, VI, 1855, p. 158, 

 pi. v, fig. 20. 



No additional information in regard to this species can be 

 given at this time except that the radula of a specimen from 

 the Tennessee River at Florence, Ala., collected by Hinkley 

 agrees with that of filosa in the characters of the central and 

 lateral teeth. A very considerable collection from the Tennes- 

 see made by Mr. H. H. Smith has not yet been worked over 

 and may add materially to our knowledge of the species when 

 critically examined. 



Rhodacmea hinkleyi (Walker). 



Ancylus {Ferrissid) hinkleyi Walker, Naut., XXI, 1908, p. 

 139, pi. lx, figs. 11-13. 



The species listed from the Tennessee River at Florence, Ala. , 

 as "Ancylus rhodaceus Walker" by Hinkley in 1906, (Naut. 

 XX, p. 40), but not described, is the same as that subsequently 

 described under this name in 1908. The radula of the Tennes- 

 see River specimens agrees with those of filosa and elatior in 

 sectional characters. 



Section Rhodocephala, n. sect. 



Shell depressed. Radula with a faintly bicuspid central 

 which has the sides of the base straight and not expanded; 

 laterals with the cusp of the mesocone extending far beyond 

 the base and overlapping the base of the central tooth. 



Type Rhodacmea rhodacme Walker. 



Rhodacmea rhodacme, n. sp. PI. I, figs. 1, 2 and 8. 



Shell depressed, conical, obovate, the greatest width being 



