THE NAUTILUS. 
65 
Succinea grosvenori Lea. 
Succinea lineata Binn. 
LIMNiEACEA. 
Family LIMN.iEID.iE 
Limncea palustris Mull. 
Limncea bulimoides Lea. 
Limncea humilis Say. 
Limncea caperata Say. 
Planorbis bicarinatus Say. 
Planorbis lentus ? Say ; young shells only. 
Planorbis parvus Say. 
Planorbis umbilicatellus Cockerell; (P. umbilicatus Taylor, Leeds 
Journ. Conch. IV, p. 351, 1885, not of Muller, 1774). Described 
from Manitoba. 
Family ANCYLIDiE. 
Ancylus rivularis Say, one specimen. 
Family PHYSIDJE. 
Physa gyrina Say, young only. 
Physa ancillaria Say. 
Physa heterostropha Say. 
Physa lordi Baird. 
PELECYPODA. 
Family CORBICULIDJE. 
Sphcerium sulcatum Lam. 
Pisidium compressum Prime. 
Family UNIONIDJE, 
Anodonta plana Lea, young. 
Anodonta ovata Lea, young. 
Only one perfect and adult specimen of Planorbis umbilicatellus 
was obtained in the river drift. It is readily distinguished from 
P. parvus Say by its narrow funnel-shaped umbilicus and higher, 
somewhat beveled whorls. It was first collected in Manitoba by 
R. M. Christy, Esq., and described by Taylor under a name al¬ 
ready widely known in the literature though generally regarded as 
a synonym of one or another Linnean species. It was re-named by 
Cockerell, in the Conchologist’s Exchange, November, 1887, p. 68. 
(W. H. D.). 
