294 THE CHICAGO ACADEMY OF SCIENCES. 



the side of an aquarium, eating everything in its path. If a 

 morsel that is distasteful is taken into the mouth, it will be 

 immediately "spit out." In one specimen examined, the man- 

 tle cavity was infested by a small parasite (or messmate) 

 which came out and went into the mantle chamber without 

 causing the snail any apparent discomfor.t. Bicarinatus is found 

 in all regions of the area, and has been collected fossil in sand 

 banks on the lake shore, north of Graceland avenue, by Mr- 

 Jensen. 



SUBGENUS PLANORBELLA Haldeman, 1844. 



"Shell few-whorled, aperture campanulate." (Dall.) 

 117. Planorbis campanulatus Say, pi. xxxii, fig. 11. 



Planorbis campanulatus SAY, Jour. Phil. Acad., Vol. II, p. 166, 1821. 

 Planorbis bellus LEA, Proc. Amer. Phil. Soc., Vol. II, p. 32, 1821. 

 Planorbis bicarinatus SOWERBY, Genera, pi. iv (non Say). 

 Helix angulata SHEPPARD, teste J. de C. Sowerby, Fauna Boreali- 



Americana, Vol. Ill, p. 315. 



Planorbis campanulatus minor CURRIER, Walker, The Nautilus, Vol. 

 VI, p. 137. 





Fto.98. 



Radula of PLANORBIS CAMPANULATUS Say. (Original.) c, central 

 tooth; 1, first lateral; 9, intermediate tooth; 13, third marginal. 



Shell: Sinistral, discoidal, more or less rounded; color 

 brownish-horn, sometimes reddish; surface shining, lines of 

 growth oblique, very numerous, raised, equidistant for the 

 most part; whorls four, discoidal. rounded above and below, 

 rarely subcarinated; spire flat, on a level with the general plane 

 of the whorls, exhibiting all the volutions; sutures deeply im- 

 pressed; periphery rounded; base of shell rounded, showing 

 two volutions with a deep umbilicus in the middle; aperture 



