THE NAUTILUS. 



breadth, 16.25 ; 

 breadth, 19.50 



breadth, 19.00 



breadth, 19.00 



aperture length, 13.00 ; 

 aperture length, 16.50 : 

 aperture length, 16.00 

 aperture length, 16.50; 



breadth 



breadth. 



breadth. 



no. 



Length, 24.00; breadth, 16.25; aperture length, 13.00; breadth, 

 8.00. 



Length, 26.50 

 11.00. 



Length, 25.00 

 10.00 mill. 



Length, 36.00 

 10.00 mill. 



Types: The Chicago Academy of Sciences, 19 specimens, 

 24504; cotypes, coll. Bryant Walker, Detroit, Mich., and Academy 

 of Natural Sciences of Philadelphia. 



Type locality : East shore Tomahawk Lake, Oneida Co., Wis. 



Animal : Similar to typical emarginata. The animals of the 

 Tomahawk Lake race are of two very pronounced colors, black with 

 white dots and bright yellow with white dots. This difference in 

 the animal is quite conspicuous rendering the light-colored speci- 

 mens less noticeable than the dark-colored in individuals against the 

 white sand of the shore. 



Jaw, Radula and Genitalia : In all respects similar to those of 

 emarginata. 



Range : Southern Quebec west to Wisconsin. 



L. wisconsinensis has been seen from but two places, Brome Lake, 

 Brome District, Quebec (Whiteaves), and Tomahawk Lake, Oneida 

 Co., Wisconsin (Baker). It doubtless lives in many lakes between 

 these two points, and has probably been identified as L. mighelsi. 



Ecology: In Tomahawk Lake, Wisconsin, this species is very 

 abundant, the shore after storms being literally paved with dead 

 shells. It lives on the sandy or pebbly shores, in water from a few 

 inches to several feet in depth. By wading along the beach thou- 

 sands may be collected. The localities in this lake are all on exposed 

 points or in curved bays where the shore receives the full force of 

 the waves. No specimens were found in sheltered places, where 

 the water was at all stagnant. As recorded by Dr. Kirtland, for 

 angulata, they were irregularly scattered over the surface, crawling 

 over the sand, where a distinct track was left, or else lying half 

 buried in the sand. The two different colors mentioned by Nylander 

 as being characteristic of the Maine emarginata were also observed 

 in the Tomahawk Lake specimens. 



Remarks : This race differs from all the other races of emarginata 

 in its very globose body whorl and rounded aperture. The race is 

 very variable, the variant being the spire which is elongated or de- 

 pressed. Some individuals approach mighelsi, but this is rare, the 

 shell being usually much more globose than that race. Angulata 

 differs in having a heavier shell, a much less globose body whorl, 

 and an elongated and angulated, instead of rounded, aperture. The 

 umbilicus is closed in anguluta while it is usually open in wisconsin- 

 ensis. The globose form will, however, separate this race from all 



