THE NAUTILUS. 113 



Length, 28.00; width, 13.00; aperture length, 17.50; width 

 8.50 mill. 



Types: Chicago Academy of Sciences, five specimens, No. 24554. 



Type Locality: Tomahawk Lake, Oneida County, Wisconsin. 



Range : Michigan and Wisconsin north of the 45th parallel of 

 north latitude. 



Records. — Michigan : Isle Royale ; various localities. (Adams ; 

 Gleason ; Walker). 



Wisconsin: Quynoch Point, Eagle Bay, and other portions of 

 Tomahawk Lake, Oneida County (Baker). 



Ecology : L. s. lilliancs is typically an inhabitant of sandy shores, 

 in shallow water, where it is subjected to heavy wave action, only 

 once was a specimen found in a still-water habitat, and this instance 

 was undoubtedly caused by drifting from its normal habitat. When 

 any number of specimens were found, the habitat was invariably an 

 exposed beach. Associated with Ulliana were Galba emarginata 

 and Flanorbis hinneyi. Individuals were observed crawling over 

 the sandy beach or attached to water-soaked logs or other shore 

 debris. 



The animal of this race exhibits two color phases, one bright yel- 

 low and the other black or giayish-black. No cause for this color 

 dimorphism was apparent. It is not protective as both forms occupy 

 the same area of white sandy beach. 



( To be continued.) 



DESCRIPTION OF A NEW SPECIES OF ANODONTA. 



BY L. S. FRIERSON. 



AnODONTA DAKOTA, n. sp. Plate X. 



Shell elliptically rounded before (slightly cut away below) dorsal 

 line nearly straight, base slightly curved. Posterior nearly straight, 

 making the shell ti-apezoidal in outline. Epidermis straw yellow, 

 with dark bands marking the rest periods. 



Umbonal ridge angular, beaks not high, with double loop sculp- 

 ture, as in Ano. grandis, Say. 



Umbos inflated, greatest diameter of shell about ^ from beak to 

 base. 



