LYMNZIDA 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 typt- 
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. stagnalis, the writer 
has given it a local name.” 
Sowerby has also described and figured a Limnea 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 pl. 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 
