POST GLACIAL BIOTA OF THE GREAT LAKES REGION 1 19 



to the Bowmanville stage or it may be later date, possibly early Toleston. 

 The presence of this mollusk so far north of its present range is of great in- 

 terest, especially in collection with the Chicago record, showing a decided 

 northward dispersal during postglacial times. It is probable that this spe- 

 cies will eventually be found in other deposits north of its present range. A 

 survey of the Green Bay deposits to ascertain the area in which this species 

 is preserved and also to discover what species were associated with it would 

 be of great interest and value. This fauna probably migrated up the 

 Wisconsin or Fox rivers. 



2. Toleston or Hammond Stage 



Some years ago Mr. A. W. Slocum, of the University of Chicago, collected 

 a number of mollusks from postglacial deposits in the city of Milwaukee and 

 its environs. These deposits are thus described by Mr. Slocum: "The Bay 

 View locality is on the bank of Lake Michigan about a mile south of the steel 

 works. It consists of a marl bed about seven feet in thickness which has been 

 uncovered by the action of the waves. The 30th Street locality is in the city 

 of Milwaukee near the intersection of 30th Street and Garfield Blvd. This is 

 a small, saucer shaped depression occupying not more than one or two acres. 

 The greatest thickness is about 13 to 15 feet and pinches out in all direc- 

 tions, roughly circular. Underneath the filling is a layer of peat about 2 feet 

 in thickness and below this is a blue clay extending down to the till beneath. 

 At the bottom of this blue clay the bones of an elephant were found. This 

 section was opened up by a sewer being run through 30th Street. 



"The shells were found at about the junction of the peat and clay. The 

 fauna at the two localities was very similar, tho the relative abundance of 

 the species varied materially. Galba palustris and Valvata sincera were 

 much more abundant at the 30th Street locality than at Bay View. Planor- 

 bis campanulatus and Physa ancillaria were among the most abundant shells 

 at the Bay View locality and were rare at 30th Street. The bivalves were 

 much more abundant at 30th Street than at Bay View. About three miles 

 west of the 30th Street locality, in the town of Wauwatosa, the marl is 

 reported to occur, although I have not seen it there." The species collected 

 are listed below: 



Anodonta species Physa ancillaria 



Sphaerium simile Planorbis campanulatus 



rhomboideum " antrosus 



Valvata sincera " antrosus striatus 



tricarinata' 3 " deflectus 



13 In the list of species first recorded ecarinate and bicarinate forms of Valvata tricarinata 

 as well as Physa heterostroplta were recorded. The Valvatas prove to be degrees of carination 

 and not true bicarinate and ecarinate varieties. The sincera is Say's species (vide Walker) 

 The Physa proves to be a form of ancillaria. 



