THE NAUTILUS. 125 



the later deposits the new form is the only large Planorbi* found, 

 an interesting case of distribution in point of time in the same 

 locality. 



Whether the new Planorbts is to be considered a variety of 

 trivolvis or a distinct species the writer is not prepared to decide 

 at the present time. In the material examined, both fossil and 

 recent, there are no intermediate specimens. Until more is 

 known it had better be considered a separate species. 



A NEW FORM OF AMNICOLA FROM THE OHIO PLEISTOCENE DEPOSIT! 

 WITH NOTES ON A PHYSA FROM THE SAME FORMATION.* 



BY FRANK C. BAKER. 



Recently, Dr. M. M. Leighton, of the Department of Geology 

 of the University of Illinois, placed in my hands for study a 

 large collection of Pleistocene fossil mollusks from a marl de- 

 posit near Rush Lake, Logan County, Ohio. One of the species 

 represented appears to be a new race of a recent species. The 

 deposit is in the older Wisconsin drift. A paper is in prepara- 

 tion describing the fauna of this deposit as well as that of a 

 possibly older deposit in Bartholomew County, Indiana, in both 

 of which a number of interesting cases of distribution occur. I 

 am indebted to Dr. H. A. Pilsbry and Dr. Bryant Walker for 

 assistance in determining the affinities of the species discussed 

 in this paper. 



AMNICOLA WINKLEYI LEIQHTONI n. var. 



Shell differing from A. winkleyi in being larger, heavier, wider 

 in proportion to its height, the body whorl being more globose 

 than in the typical form; there are 4^ whorls, the upper part of 

 which is somewhat flat-sided just below the suture; this is 

 especially marked on the last whorl of some individuals; the 

 spire whorls are rounded and the sutures deeply impressed; the 

 first whorl is flatter than in winkleyi ; the umbilicus is wider and 

 deeper and the aperture is wider in proportion to its height than 

 In winkleyi. 



* Contribution from the Museum of Natural History, University of Illinois, 

 > T o. 10. 



