SEVENTH ANNUAL MEETING 77 



a quantity of dead shells, drift wood, and other debris, and not 

 colonies of living shells. The mastodon skulls were found in 

 and under the stratum of semi-ligneous peat, showing that 

 these animals waded into the river after the shells were de- 

 posited. They were probably caught in the boggy bottom and 

 were drowned. 



The multitude of lakes which dot the surface of Berrien, 

 Cass and Van Buren counties, especially in the swampy area 

 near the Dowagiac and St. Joseph rivers, nearly all have marl 

 deposits correlative with the later stages of the Great Lakes 

 history. Many of these date from the glacial Lake Dowagiac, 

 which had its outlet through the Kankakee River, while others 

 are relics of the early stage of Lake Chicago when an arm ex- 

 tended into Michigan and up the valleys of the PawPaw and 

 Black rivers. 



2. Magician Lake, Cass County 



In the northwestern part of Cass county, and also partly in 

 Van Buren county, is a lake of considerable size, known as 

 Magician Lake. This body of water empties into the Do- 

 wagiac River through Dowagiac Creek. Swampy tracts and 

 old shore lines indicate this lake was once considerably larger 

 and deeper. On the north shore, and about midway of the 

 lake, near the summer resort known as Magician Beach, is an 

 old embayment which is a swampy terrace about two feet 

 above the water line. The upper three feet are peaty and 

 boggy ; beneath this stratum is a marl bed of unknown depth, 

 which is filled with mollusks, of which the following species 

 have been identified : 



Unio, fragments 



Sphaerium simile (Say) 



Pisidium compressum Prime 



Pisidium variabile Prime 



Pisidium noveboracense Sterki 



Pisidium splendidulum Sterki 



Pisidium adamsi affine Sterki 



Valvata tricarinata Say; Central carina almost absent in some specimens. 



Ammicola limosa (Say) 



Ammicola lustrica Pilsbry 



Paludestrina nickliniana (Sea) 



Physa integra Hald 



Physa ancillaria Say 



Physa walkeri Crandall 



Physa gyrina Say 



Planorbis antrosus Conrad 



Planorbis antrosus angistomus Hald 



Planorbis parvus Say 



Planorbis deflectus Say 



Planorbis hirsutus Gould 



Planorbis exacuous Say 



