4 I'ni-ccrsily of Michigan 



So far as this shows anything, it would seem ' that the 

 average shell in this series is both larger and higher than the 

 average Upper Peninsula specimen ; that it is wider and more 

 depressed than the average Charity Island shell, and also a 

 trifle wider and more depressed than the average Lower 

 I'eninsula specimen. It must be said that the chief impression 

 made by an inspection of the whole series was that of its ex- 

 treme variability, giving the appearance of coming from a 

 transition region. This, however, may be the result of varia- 

 tion in local conditions of environment rather than of geo- 

 grai^hical situation. 



2. Polygyra fraterna (Say). — Schoolcraft: From decay- 

 ing wood on high ground. Alger : From decaying maple log. 

 Chippewa : From spruce-cedar swamp and hardwood forest 

 near \'ermilion. 



All the specimens are umbilicate, and the occurrence of 

 this species W'ith the preceding one again bears out the con- 

 clusions of Dr. Walker m regard to their coincident distribu- 

 tion (Walker, 1905, pp. 92-93, PI. I). 



3. Vitrca haiiniionis (Strom). — Schoolcraft: Found un- 

 der logs, on dead leaves in a pond, and under log on a wooded 

 sand ridge. 



4. Vitrca biiuicyaiia (Mse.). — Schoolcraft: One lot of this 

 species from rotten wood and leaves in the hardwood forest. 

 It has been listed as a boreal species (Walker. 1908, p. 282). 



5. Vitrca fcrrca (Mse.). — Schoolcraft: Three specimens 

 were collected in the hardwood forest among leaves and de- 

 caying wood. 



6. Bitconulus chcrsiiiiis polygyralits Pils. — Schoolcraft: 

 Under logs. Alger : In old dead logs. 



7. Zonitoidcs arbon^a (Say). — Schoolcraft: Eight lots of 

 this common species were collected on logs, on sand ridges, in 



