432 THE CHICAGO ACADEMY OF SCIENCES. 
once thought to be a form of Galba contracta, but the above disposition 
now appears to be the most logical. 
Canadensis is a distinct race of emarginata and will doubtless be 
found to cover a wide range when it is sufficiently differentiated from 
the other races of emarginata. The name emarginata has been made to 
cover specimens of binneyt, catascopium, palustris and mighelsi, besides 
several other forms, and has been quoted from Maine to Alaska. So 
far as known no form of emarginata or its races, has been found west 
of Minnesota or south of Michigan and Wisconsin. It is a type of 
mollusk almost peculiar to the Great Lakes and the streams emptying 
into them. It is also abundantly represented in the upper waters of 
the Mississippi Valley drainage, in Wisconsin and Minnesota. The five 
races recorded in the present monograph seem to be well characterized 
representing five types of variation about each of which numerous 
mutations have formed. 
Galba emarginata ontariensis (‘“Muhlfeldt” Kuster). Plate 
XLV, figures 21-28. 
Limne@us ontariensis MUHLFELDT in Lit., KUsTEr, in Chemn., ed. 2, p. 45, 
1862. 
Limnea emarginata var. A. ontariensis Binney, L. & F.-W. Sh. N. A, 
Il, p. 52, 1865. 
Limnea emarginata BAKer, Bull. Chi. Acad. Sci., II, pl. 1, fig. C, 1900. 
Limnea catascopium Waker, Nautilus, VII, p. 128, 1894 (part). 
SHELL: Ovate-conic, rather thick; periostracum light yellowish 
horn or purplish white ; surface sculptures as in emarginata canadensis ; 
there are from four to six rest varices on the shell; nuclear whorls 
as in canadensis; whorls 51%, the spire whorls flatly sloping, the body 
whorl very convex; spire short, broadly acutely conic; sutures usually 
not much impressed; aperture semi-oval, broadly rounded below and 
much narrowed and angulated above, about as long as the spire; the 
aperture is frequently much expanded appearing to flare markedly; 
outer lip with an internal varix; inner lip broad, thick, closely ap- 
pressed to the columellar region, completely closing the umbilicus; the 
parietal callus is usually well marked and is sometimes very heavy; 
the inner lip is usually compressed at its junction with the parietal 
wall forming a plait of variable distinctness ; axis twisted. 
Length. Width. Aperture length. Width. 
17.00 10.00 10.50 6.00 mill. Buffalo. 
15.00 9.00 9.25 rity) ae 7 
18.50 11.00 12.00 6:50. Fort Erie. 
17.00 9.00 9.75 Ata oS Y 
17.00 10.00 10.00 5.50 “ Saginaw Bay. 
14.00 9.00 9.00 5.00 * 3 a 
15.50 9.50 9.75 5.00 “ “ “ 
