JOURNAL OF CONCHOLOGY. 35 1 



DESCRIPTION OF A 

 NEW SPECIES OF PLANORBIS FROM MANITOBA. 



By JOHN W. TAYLOR. 



(^ c^ 



Planorbis umbilicatus. 



Mr. R. M. Christy, who has paid several visits to Manitoba, 

 kindly placed his collections in my hands for examination. 

 Amongst the Planorbes from Brandon, Birtle, &c., there was a 

 form which I could not with propriety refer to any described 

 species, I therefore propose to name it as above. Mr. Nelson, 

 who has studied the Limnaeidae, agrees with me in regarding 

 the specimens as distinct from any previously described 

 species. 



Shell somewhat flat above, but slightly sunk in the centre, 

 convex below, greyish-white, somewhat glossy, closely and dis- 

 tinctly striate in the line of growth, with stronger ridges at 

 intervals, most visible on the under side. Periphery rounded, 

 but slightly compressed at each side. Suture rather deep. 

 Aperture oblique and somewhat cordiform. Umbilicus deep 

 and narrowly funnel-shaped. Whorls 4^, compact, gradually 

 increasing in size and faintly keeled or angulated on upper 

 side. Diam. 6)4 mill., alt. 2 mill. 



The species bears some resemblance to P. parvus Say, 

 but its somewhat funnel-shaped umbilicus is sufficient to at once 

 separate it. 



