■n 



The Nautilus. 



Vor,. XViri. JANUARY, 1905. No. 9. 



ON AN INTERESTING FOSSIL UNIO FROM WISCONSIN. 



BY GEORGE WAGNER. 



A little over a year ago Mrs. George Marston, of Quincy, Illinois, 

 presented to the University of AVisconsin the mollusca brought to- 

 gether by her late husband, an ardent and an able collector of our 

 Wisconsin forms. The collection was placed in my hands for ar- 

 rangement. In looking it over I was immediately attracted by a 

 single somewhat broken valve of a Unio, evidently fossilized, and 

 the only fossil form in the collection. 



Mrs. Marston had very kindly, and very wisely, sent with the col- 

 lection all of her husband's correspondence relating to it. In look- 

 ing over the letters I came across a copy of one written by Mr. 

 Marston, aitd containing the necessary locality data for this shell, 

 tj According to tiiis letter the ^-liell was found about 1889 in the 

 ' city of Green Bay, Wisconsin, during excavations for the city water- 

 works reservoir. It came from a de|)tli of al)out fifteen feet below 

 the surface, and presumably from the till. 



'iiAs Mr. Marston well knew, the shell is wholly uidikeany Unionid 

 now. found in Wisconsin. It is a left valve, (pjite heavy hut very 

 brittle. When found, tiie outer surface still retained most of tin- 

 epidermis, but this has almost entirely disap|ieared. The height is 

 70 mm., thfe breadth of the single valve' approximately 22 mm. 



The shell when complete was very ievidently smooth, with m rather 

 elliptical -outline. The wall is thick but thins down cniisideriil'ly 



