New species of Fresh Water Shells. 343 
- Inhabits Alabama river, adhering to pebbles on the bars. Cabinet 
a the Academy of Natural Sciences of Philadelphia. 
Unto sUBTENTUS. Say. var. Pl. 1. fig.3 
‘This beautiful variety of the U. subtentus was found me in the 
Tennessee and Elk rivers. The annexed delineation of the species 
is probably better than any hitherto given. 
‘Unsio MYTILLOIDEs. Raf, var. Pl. 1, fig. ie 
q obtained this shell in the Alabama river. Its characters appear 
to be intermediate between U. ellipsis, Lea, and U. mytilloides, 
Raf., yet is doubtless identical with the latter species. 
SUPPLEMENT. 
PLANORBIS ANTROSUS. 
Shell dextral, not depressed ; whorls three; spire profoundly in- 
dented, or concave, with the summit of the body whorl angular ; ‘in- 
ner volutions angulated ; umbilicus profound, with the margin and 
inner volutions angulated: body whorl abruptly dilated near hosed 
—— aperture longitudinally subpvate, dilated. 
_Meuania coneesra. 
‘Shell subulate, with about nine volutions, the lower ones obscurely 
angulated, those of the spire becoming acutely carinated towards the 
apex; suture well defined ; body whorl obscurely sub-angulated ; 
aperture longitudinal, elliptical: 
Prysa POMILIA. 
Shell with four volutions, horn colored and polished ; spire short 
conical ; body whorl ventricose ; aperture patulous.—Remark. It 
saibles P. heterostropha, Say, but is much smaller and thinner. 
These three univalves inhabit Randon’s creek, near cacao 
Alabama, adhering to Limestone rocks. 
(Tobe continued.) 
