OF NORTH AMERICA. 431 



emarginata. In Owasco Lake, New York, this race occurs in vast 

 numbers and great variety of form. The shells vary from rather long 

 and narrow, with acuminate spire, to short and convex with very short 

 spire. The columella is more or less plicate and the aperture varies 

 from roundly ovate to elongate ovate. 



This is the race which has usually been called typical emarginata; 

 an examination of Maine and Wisconsin material, in connection with 

 Say's original description, figures and autotypes, shows that the typi- 

 cal form is not the one with the acuminate spire, but with the broad and 

 depressed spire. Say's figure emphasizes the globoseness of the whorls. 

 Certain specimens of this race may be confused with catascopium, and 

 may be known from that species by their large size, wider and heavier 

 inner lip, longer spire and (usually) absence of a plait. 



Sowerby's description of his canadensis is as follows : 



"Shell pyramidal, anteriorly inflated, rather thin, polished, horny; 

 spire attenuated, whorls four, rather rounded, the last inflated; anter- 

 iorly slightly acuminated, a little excavated behind the columella ; aper- 

 ture auriform, inner lip broad, columella thick, strongly plicated ; outer 

 lip expanded, reflected, thickened within. Habitat Canada." Sowerby 

 further adds, "Finding this shell in the British Museum without a 

 name, and thinking it sufficiently distinct from L. st agnails, the writer 

 has given it a local name." 



Sowerby has also described and figured a Limncea barbadensis 

 which appears to be the same as canadensis, judging by the description 

 and figure. It is not the type of shell that inhabits the West Indies and 

 it is exactly like the shells of the emarginata group. A mixing of labels 

 doubtless accounts for its description as a Barbadoes shell. It prob- 

 ably came from Canada or the northern part of the United States and 

 there is little doubt of its being referable to canadensis. 



Specimens of canadensis from Michigan have been compared. with 

 Sowerby's types in the British Museum, and the shells referred to 

 canadensis from New York, Michigan and Minnesota, conform closely 

 to the form of these shells (see pi. XLIV, figures 19-23). Certain 

 shells from Bear Lake, Michigan, are referred provisionally to variety 

 canadensis (plate XLV, figures 18-20). These are very narrow with 

 an elongated spire and compressed whorls. The four specimens figured 

 are either bleached or fossil individuals and are evidently immature. 

 Typical canadensis (plate XLV, figures 14-15) inhabits this lake and 

 exhibits a variation of the body whorl from subglobose to narrow and 

 compressed (plate XLV, figures 16-17). It is easy to connect these 

 narrower forms with the very narrow specimens figured. These were 



