392 



LAND AND FRESH-WATER SHELLS OF N. A. [PART IV. 



Anculotus nif/rescens. — Shell subconical, truncated or much eroded 

 at the apex; superior whorl hardly convex; body-whorl: elongated, 

 contracted above on the labrum ; columella flattened, obtusely rounded 

 at the base ; aperture obovate, rather more than half the length of 



Fig. 759. Fig. 760. Fig. 763. Fig. 7GL Fig. 762, Fig. 764. Fig.7G5. 



Fig . 766. 



the shell ; epidermis blackish ; within dark purple. I am indebted to 

 Mr. Hyde for this shell; he informs me it inhabits rivers in Maryland. 



— Conrad. 



The cut (fig. 762) is from a type specimen. 



Aiiculosa trivittata. — Shell elliptical; whorls about five, convex; 

 suture impressed; spire short, often eroded, and about the length 

 of the aperture ; inner lip arcuated, with a callus ; aperture oval, 

 rounded beneath, acute above ; color dark olive, with three dark 

 purple, I'evolving lines on the carina, the central band very narrow. 



Length of shell, -5 of an inch. Length of aperture, "25 of an inch. 



Observations. — These species were obtained from Cranes- 

 port, in company with the preceding. In some, the bands 

 are obscure or wanting. It appears to bo closely allied to 

 A. melanoides of Conrad, but is distinguished by the greater 

 number of its volutions. — DeKatj. 



The above figures will suffice to show the mutation of form 

 from the carinate varieties, througli trivittata, DeKay, and ni- 

 (jrescens, Conrad, into the small shells with a toothed columella. 



The following is Mr. Conrad's description of 



Anculotus monodontoides. — Shell subglobose ; body- whorl ventri- 

 cose, not abruptly rounded above ; apex eroded ; columella with a 

 Fig. 768. Fig. 767. ^^^'S^j pyramidal tooth at the base ; epidermis horn- 

 j^™^. colored, with obscure bands; aperture efllise. 



Habitat. — Inhabits streams in Virginia; Mr. Hyde. 

 Observations. — I received a specimen of this curious 

 species from Prof. Green of Jefferson college. — Conrad. Fig. 770. Fig. 769. 



Figure 770 is from a type specimen ; figure 7G8, 

 light green in color and a much thinner sliell, was 

 collected by me at Richmond, Virginia. Entirely identical 



