NATURAL SCIENCES OP PHILADELPHIA. 273 



backwards, behind the spire, which it ascends to about half its 

 height, and then bends down to near the suture of the body whorl. 

 Unlike the first, and like the second, of its congeners, it has the 

 whole spire enveloped in a plate, which might more probably be 

 described as a posterior extension of the body whorl, carrying 

 the suture to the extreme apex. The lines of growth ran from the 

 top of the spire to the anterior end of the shell. It carries none of 

 the tubercles seen in Calyptraphorus and Tessarolax, and seems, 

 unlike most of the other genera of the family, to have had a simple 

 outer lip, neither thickened, digitate, nor notched. 



0. inornatus. 

 Dolophanes, Gabb, pi. 11, fig. 7. 



Shell elongate oval, spire elevated; with a minute, imperforate 

 umbilicus ; aperture semi-oval, inner lip acute, sinuous ; anterior 

 end of the aperture terminating in a short, not emarginate canal. 



The first impression produced on looking at this little shell, is 



that it is probably a Melania. It is however undoubtedly marine, 



and it has a grouping of characters which ally it so closely to 



Struthiolaria, that I am convinced that it is a nearly related 



genus. Its spire is very like that of many of the species of the 



Strombidse, and, in the details of its mouth, it differs only from 



Struthiolaria in having a thinly encrusted inner lip, an acute outer 



lip and an obsolete umbilicus, instead of the thickened margins 



and no umbilicus of that genus. 



D. melanoides. 



ACT2E0NID.E. 



Act^onidea, Gabb, pi. 11, fig. 8, 8 a. 



Shell oval, elongate ; aperture narrow, outer lip simple ; colu- 

 mella slightly encrusted, bearing one large transverse fold in the 

 middle and truncated in advance. Ornamented by revolving ribs. 



This genus is an Actdeon except that it has a single large fold on 

 the middle of the inner lip, and the columella is truncated as in 

 Achatina. 



A. oryza, Gabb. 



BULLID.E. 

 Cylichnella, Gabb, pi. 10, fig. 2. 



Shell sub-cylindrical, spire sunken ; mouth narrow behind, 

 widened or advance ; columella with two folds. 



This genus has the external form of Cylichna, but it has two 

 distinct folds. The upper one is sharp and prominent like that of 



