THE NAUTILUS. 3 



the tree to full view of the eager collector. The great range of 

 variation in this species, not only in color but in size and form 

 causes one to wonder if there are not possibly several distinct species 

 included in the one comprehensive name of " alauda." There is 

 also there, in these woods, but rather sparingly, Pleurodonte mar- 

 ginella Gmel. of a very dark color form. These also live on the 

 trees, but only on the large trees and then invariably on the trunks. 

 They look just like great big buttons and may be detected a hundred 

 feet away. On the ground, quite common, were Pleurodonte auricoma 

 provisoria Pfr. and a Helicina that we may call, for the present, 

 submarginata Gray, also, Oleacina subulata Pfr. On the tree trunks, 

 low down near the ground, very strictly of social habit, were Mac- 

 roceramus pictus (Gundl.) Pfr. and, more commonly distributed, the 

 Chondropoma revinctum Poey. 



We answered the call of the more distant mountains later and I 

 would like to tell of that trip when I shall have had time to identify 

 the material collected. That is up in the " picta " country. I know 

 of nothing more wonderful for jaded nerves and " that tired feeling" 

 than to range the woods and banana fields for Polymita picta. 



NOTES ON CIRCINAKIA CONCAVA (SAY) FROM SHEBOYGAN COUNTY. 



MICHIGAN. 



BY H. BURRINGTON BAKER. 



Circinaria concava was considered to be a typical shell of the 

 Upper Austral, and in the southern peninsula of Michigan was not 

 known to extend much farther north than the old Saginaw-Grand 

 River outlet. In consequence, it was a surprise to find it last sum- 

 mer near the north shore of Burt Lake, Cheboygan County, about 

 one-hundred and fifty miles north of this line. Even more peculiar, 

 however, was its habitat, as it was living in and along the edge of a 

 large, boreal, cedar-spruce-fir (Thuja-Picea- Abies) bog, along with 

 such a typically boreal species as Pyramidula astenscus (Morse). 



A quite thorough search of the hardwoods and other transition 

 habitats of the region failed to reveal this shell, so it appears we 

 have an austral shell living in a boreal bog in a transition region. 

 One is tempted to conclude that this species, weakened by living too 

 far north, is unable to cope with its competitors in the more favor- 



