Geological Survey of Alabama. 29 



a thickened, circular peristome. Umbilicus generally covered by this 

 deposit. 



Has a general resemblance to the genus Pterocheilos, Moore, by reason 

 of its peculiar aperture. This deposit or filling in is not accidental, as 

 Dr. O. Meyer has, in his collection, a very young shell of similar form, 

 either the same or an allied species, showing the same peculiarity. It is 

 from the Claiborne sand-bed. 



This young shell has the umbilicus exposed, but the aperture is even 

 more filled in than my type specimen, and the spire is flattened. This 

 genus would be next to Ancillaria in the Aneillarince. 



EXPLERITOMA PRIMA, n. Sp. PL 5, fig. 1. 



Shell rounded-elliptical ; surface probably smooth ; spire moderate ; 

 whorls, four to six ; a well defined but small sulcus upon the lower half 

 of the body whorl ; base canaliculate, but filled up with a deposit from 

 the aperture. 



Aperture elliptical, about one-half the indicated size, caused by a thick 

 deposit covering the whole peristome, except a small space on the outer 



HP. 



Locality. Branch of Satilpa Creek, Ala., in ferruginous sand-bed of 

 Claiborne Group. 



Only one specimen found, and that is considerably eroded. The back 

 of the shell looks like a specimen of Ancillopsis subglobosa, Con. 



PLEUROTOMA HEILPRINI, Aldr. PL 1, fig. 15. 

 Pleurotoma Heilprini, Aldr. J. C. S. N. H., July, 1885. 



PLEUROTOMA AMERICANA, Aldr. PL 1, fig. 16. 



Triforis Americanus, Aldr. J. C. S. N. H., July, 1885. 



Prof. Heilprin pronounces this species, which I described as a Triforis, 

 to be a reversed Pleurotoma. While the lines showing the slit are not 

 very apparent, yet, in deference to his opinion, the change is made. It 

 is so different from most of the Triforis group, that it is much more likely 

 to be nearer its true place than before. As the shell is quite common in 

 Jackson, and always reversed, it is probably a good species. 



PLEUROTOMA ANITA, Aldr. PL 2, fig. 3. 

 P. anita, Aldr. J. C. S. N. H., July, 1885. 



