57 
(Dali); Winnipeck river (possibly meaning Winnipeg river) and lake, 
Rainy lake, Lake of the Woods (Say); Minaki, Winnipeg river, Sand lake, 
Winnipeg river, White Dog, Winnipeg river, Sword lake, near Minaki, 
Fox lake near Wade, all Ontario (Mozley). 
Corpulentus is at once known by the rather sharp dorsal and ventral 
carina and peculiar rib-like spaced sculpture of the body whorl. The 
radula is different from that of trivolvis as are also the carinated whorls and 
sculpture. Both species, also, occur in the same lake area, as noted in 
Bamaji and St. Joseph lakes. There is some variation in the sculpture and 
in the axial height of the body whorl, but all of the material examined agrees 
in the carinated and flat-sided whorls so characteristic of the species. The 
race vermilionensis F. C. Baker, at present known only from lake Ver- 
milion, northern Minnesota, appears not to be represented among any of 
the Canadian specimens. It differs from typical corpulenta in its greater 
axial height and in the flatter, even concave body whorl, and in the flatness 
of both spire and base whorls (See Baker, 1029a, p. 131). 
Helisoma (Planorbella) campanulata canadensis var. nov, Plate II, 
top row 
Shell resembling that of Helisoma campanulata wisconsinensis (Win- 
slow), but always much smaller. There are 5f whorls, slightly carinated 
above, rounded below; umbilicus deep, showing three full whorls; spire 
elevated above the general plane; sculpture coarse, rib-like; aperture as 
in wisconsinensis. 
Height 6 0; Gr. diam. 11*5; Les. diam. 9*2; Aper. height 41; Diam. 3-0 mm. 
Type. 
Height 5-2; Gr. diam. 10*5; Los. diam. 8*5; Aper. height 4-0; Diam. 2*8 mm. 
Para type. 
Type locality: Bamaji lake, northern Ontario. Types: Mus. Nat. Hist. 
Univ. 111., Z30721; Cotypes, National Museum, Canada, Molluscs, No. 4378. 
This form of campanulata is another of the almost endless variations 
of these northern planorbes. It appears to be a miniature wisconsinensis 
and might bo referred to this variety but for its uniformly smaller size, 
the Wisconsin form measuring 8 mm. in height and 16 mm. in diameter 
in its most common form. Smaller individuals occur among the specimens 
from the type locality (Little Arbor Vitae lake, Vilas county, Wis.), but 
. these are invariably associated with the larger form. The largest examples 
of wisconsinensis are found in Tomahawk lake, Oneida county, Wis. 
The small form herein called canadensis appears to be characteristic 
of the lakes of northern Ontario, only one specimen in a series of 35 from 
this region even approaching wisconsinensis in size. This specimen measures : 
height 6, greater diameter 12*8 mm. It was found in Hamilton lake. The 
collection includes material from the following localities: Hamilton, Cat, 
Bamaji, Kimmewin, Kapikik, and St. Joseph lakes. On the previous trip 
(1928) the same form was found in Trout lake, near the International Line, 
Ontario, and in lake La Croix, Rainy River district. 
Previous records of campanulata from Keewatin and other parts of 
central and northern Canada probably include this variety, if they were 
not founded entirely upon it. Such are Whiteaves' records from lac Seul, 
Kawinogans, Elbow, and Attawapiskat rivers, lake St. Joseph, and Winisk 
river. Some of Dali’s records from English river, Moose Factory, Great 
