62 
Physa (Physodon) gyrina (Say) 
Ramaji, Botsford, Hamilton, Pashkokogan, Cat, Fitchie, Kimmewin, 
and St. Joseph lakes. 
A few physae, all beach shells, are referred to gyrina by Mr. Clench. 
They all have very thin shells, due to the absence of limestone rocks sur- 
rounding these lakes. Mr. Clench says of these shells “The specimen sent 
has the sculpture and general shape of gyrina, lacking only the thickness 
of the shell, a very variable character in this genus.” 
This is evidently the species recorded as heterostropha by Whiteaves 
from lake St. Joseph, . lac Seul, Machawaian lake, Attawapiskat river, 
Wapikopa lake, and Winisk river. Also Albany river and Knee lake. 
Gyrina is listed from several places in Manitoba by Mozley. The reference 
to heterostropha is probably founded upon some other species, as this is an 
eastern form, not authentically recorded from the central states. Physa 
inlegra Hald. and Aplexa hypnorum (Linn.) are listed by Mozley from 
Manitoba. Dali’s records all need revision since they are founded on the 
old lists of Whiteaves and others and also on a misconception of the species. 
Aplexa hypnorum is listed by Whiteaves from Harricanaw river near 
Hannah bay and by Dali from York Factory. The physoid fauna of 
Ontario and adjacent territory is greatly in need of revision based on our 
modern conception of the family. The many lakes should contain some of 
the varieties recorded from Wisconsin, Michigan, and Minnesota, as well as 
others not yet recorded. 
Land Mollusca 
A few land molluscs, mostly from beach debris associated with fresh- 
water species, were collected by the Cahn party. These are listed below. 
Gonyodiscus anthonyi (Pilsbry) 
Shore of lakes St. Joseph and Botsford. Living under rock in spruce 
forest bordering Kogik lake. It is interesting to note that these are typical 
anthonyi and not the carinated form catskillensis , characteristic of high 
latitudes. 
Retinella hammonis (Strom.) 
Under rock in spruce forest bordering Kogik lake. 
Zonitoides arborea (Say) 
Beach debris on lake St. Joseph. 
Succinea retusa Lea 
Beach debris on lakes Bamaji and Kapikik. 
Succinea avara Say 
Beach debris on lakes Kapikik, Bamaji, and Pashkokogan. 
BIBLIOGRAPHY 
Adamstone, F. li. 
1923. “The Distribution and Economic Importance of Molluscs in Lake Nipigon"; 
Univ. Toronto Studies, 14, pp. 33-100. 
Laker, Frank Collins 
1900. “The Gross Anatomy of Limnaea Emarginata, Hay, Var. Mighelsi, Binney"; 
Bull. Chi. Acad. Hci., II. pp. 189-224. 
1909, “Note on Planorbis Bmneyi Tryon"; Nautilus, XXIII, pp. 41-42. 
