THE NAUTILUS. 7 



WOTES ON POST-GLACIAL MOLLUSCA. I. EMMET COUNTY, MICHIGAN. 



BY FRANK C. BAKER. 



Authentic records of life from the deposits laid down by the waters 

 of the Glacial Great Lakes are, apparently, exceedingly scarce. It 

 is proposed to record such as have come to the writer's notice. A 

 recent canvas of the available literature revealed the fact that little 

 real work has been done relative to this subject. This is especially 

 true regarding records bearing upon interglacial time, where the 

 majority of records available are " wood and unios," which are said 

 to have occurred in well borings. It is needless to add that this 

 material would be of the utmost value if properly identified. 



Some years ago Mr. A. W. Slocum, of the Fried Museum of Nat- 

 ural History, collected a number of mollusks from marl beds at Oden 

 and Kegomic, Emmet County, Michigan. Oden lies between the 

 Algonquin and Nipissing beaches, while Kegomic is on the old lake 

 floor. These marl deposits are reported to be upwards of sixty feet 

 in thickness, and the Kegomic deposit probably represents both the 

 Algonquin and Nipissing stages. The large lakes, Burt and Mullet, 

 as well as the smaller lakes, Crooked, Pickerel, etc., are relics of the 

 wide strait which, during these late stages, connected Lakes Huron 

 and Michigan and separated portions of Emmet and Cheboygan 

 counties from the lower peninsula, the former territory forming an 

 island, with the straits of Mackinac on the north. 



The following species of mollusks have been identified from the 

 two localities. 



Oden. 



Sphaerium striatinum (Lamarck). 

 Physa niagarensis Lea. 

 Planorbis autrosus Conrad. 

 P/anorbis campanulatus Say. 

 Galba emarginata canadensis (Sowb.). 

 Lymnaea stagnalis appressa Linne. 



Kegomic. 



Sphaerium striatinum (Lamarck). 

 Pisidium compressum (Prime). 



