POSTGLACIAL BIOTA OF THE GREAT LAKES REGION 133 



County, farm in Otter Creek Township; Wabash County, east half section 18.T. 27. R. 8, 

 near Dora, Pleasant Township, under 5 feet of muck; Wayne County, on Nolans Fork, near 

 Webster. 



Castoroides ohioensis (pages 766-768). 



Boone County, no locality; Cass County, 2-3 miles south of Logansport, 7 feet below 

 surface, lying on fine sand, covered with 1 foot of solid gravel, 3 feet of clay and 3 feet of 

 alluvium; Grant County, near Greenville; Madison County, near Summitville; Wayne 

 County, two miles east of Richmond, in fish pond with decayed mastodon bones. 



IV. MICHIGAN 



Several deposits have been observed in Michigan which contain an abun- 

 dance of molluscan life. Some of these deposits are referable to the Lake 

 Warren, Lake Algonquin, and Nipissing Great Lakes stages. Others are of 

 uncertain age, tho all are postglacial and pre-recent. 



1. Lake Warren 



Near Badake, in Huron County, (section 24) alternating beds of marsh and 

 marl deposits (two beds of each) have been observed. In section 32, close to 

 the stone wall, marsh deposits also occur. 51 The deposits first mentioned are 

 760 feet above tide or about 180 feet above the present level of the lake. They 

 are referred by Lane to the Forest beach of Lake Warren. The species con- 

 tained in the two lower deposits are as follows: 



Sphaerium simile ( = sulcatum) Valvata tricarinala 12 



Musculium secure Physa ancillaria 



Pisidium abdilum " gyrina 



" compressum Ancylus species 



variabile Planorbis antrosus 



" contorlum " campanulatus 



" contortum, var. " defiectus 



" rotundatum Galba obrussa 



" scutellatum Galba species 63 



Amnicola limosa Zonitoides arborea 



2. Lake Chicago (Toleston Stage) 



Two miles west and a little north of Buchanan, Berrien County, is a stretch 

 of low land known as Bakertown marsh. The marsh was previously a lake 

 about three miles long and a mile wide, but is now grown up in marsh grass 

 and is practically dry. A ditch about a mile in length drains the marsh and 

 exposes the strata, as noted below : 



VIII Marsh bog 16 inches 



VET Recent peat 20 " 



" GeoL Surv. Mich., VII, part ii, p. 247. 



"Evidently includes tricarinala and its varieties. Walker says, "exhibiting all stages 

 from the unicarinate to the tricarinate form, — none ecarinate. " 

 63 Imperfect specimens, lacking the spire. 



