90 



The Ottawa Naturalist. 



[August 



published a "List of the Shells found about Ottawa" in which 

 he cited L. humilis Say and L. caperata Say but not L. umbili- 

 cata. Shortly after this he sent to me a set of the Ottawa 

 "humilis. " 



In revising my LymncBidce recently, I found tliat these 

 shells were not humilis but were utnbilicata. A similar discovery 

 in regard to several lots of " humilis " from Maine 

 and its recognition from one locality in Michigan, would indicate 

 a probable range for this form from New England westward to 

 Michigan and northward into the St. Lawrence Vallev. Its 

 occurrence in Canada is definitely determined by Mr. Heron's 

 specimens. 



In view of the confusion which has existed in regard to 

 these three species L. umbilicata, caperata and humilis, it would 

 seem worth while to call attention to their differences, so that 

 Canadian collectors may more readily distinguish them. 



Fig. 1. 

 Fig. 2. 

 Fig. 3. 



L. humilis Say. Clinton River, Macomb Co., Mich., 

 Alt. 10, diam. SI mm. 



L. caperata Say. Hammond. Ind. 

 Alt. 12^, diam. 6 mm. 



L. umbilicata C. B. Ads. 

 Alt. 9, diam. 5 mm. 



Ottawa, Ontario. 



As shown by the figures, the three species differ radically in 

 shape and considerably in size. The surface sculpture is also 

 quite different. 



Caperata is uniformly larger than the others and is well 

 characterized by the elevated and revolving lines which are 

 verv conspicuous in young shells and more or less persistent 

 in maturity and, when present, give the surface a velvety 

 appearance. 



Humilis is so different in shape from the others that it seems 

 strange that any confusion should have occurred. It never has the 

 thickened lip so common in both of the other species and its 



