68 THE NAUTILUS. 



NOTES ON POST-GLACIAL MOLLUSCA, II : WAUKESHA COUNTY, 



WISCONSIN. 



BY FRANK C. BAKER. 



A few years ago Mr. Frank M. Woodruff secured a number of 

 post-glacial mollusks near Waukesha, Wisconsin. This locality is 

 in the northwestern part of the County, and is well within the area 

 of the late Wisconsin ice sheet. The body of water in which the 

 mollusks lived was one of the many small lakes left by the retiring 

 lobes of the Lake Michigan glacier. It has not been possible to 

 correlate this marl deposit with any one glacial stage of Lake Chicago. 

 Mr. Woodruff reports the shells as very abundant. Eight species 

 have been identified, as noted below : 



Amnicola walkeri Pilsbry. 



Physa ancillaria warreniana Lea. 



Physa walkeri Crandall. Several scalariform individuals. 



Planorbis campanulatus Say. 



Planorbis bicarinatus Say. 



Planorbis parvus Say. 



Planorbis exacuous Say. 



Galba nashotahensis Baker. 



A NEW SINISTKAL AMASTRA. 



BY C. MONTAGUE COOKE, PH.D. 



AMASTRA PILSBRYI n. sp. 



Shell imperforate, sinistral, elliptical with conic spire which is 

 somewhat contracted near the summit. One cotype is of an old gold 

 color, streaked with chestnut behind the outer lip, and with the spire 

 brownish ; the other (dead) cotype is wax yellow in front of the 

 aperture, elsewhere with a yellow gleam under a pale tawny 

 cuticle, the last third of the last whorl chestnut. Surface of the last 

 whorl semi-matt, the spire more shining ; smooth to the eye, but 

 under the lens unequal growth-wrinkles are seen. Embryonic 2^ 



