LYMN^EID^E OF NORTH AMERICA. 345 



Types : Exilis Lea, one specimen, No. 119481, Smithsonian In- 

 stitution ; zebra Tryon, four specimens, Academy of Natural Science, 

 Philadelphia, No. 58629. 



Type Locality : Exilis, near Cincinnati, Ohio ; zebra, Minnesota. 



Animal, Jaw, Radula and Genitalia : Not examined. 



Range (Figure 39) : Ohio to Kansas, northward to northern 

 Minnesota, and northern Michigan. 



Exilis is typical of the humid divisions of the Transition and 

 Upper Austral life zones, from whence it has crossed into the southern 

 part of the Boreal (Canadian) life zone, in Minnesota and Michigan. 

 Tt is a Mississippi Valley and Great Lakes species, common to the 

 Canadian and Upper Mississippian regions. Its differentiation from 

 reflexa will doubtless extend its range. 



RECORDS. 



UNITED STATES. 



Illinois: Cook Co. (Baker); Calumet River and Calumet Lake, Cook 

 Co. (Baker; Calkins; Walker); Mercer and Winnebago cos. (Ferriss) ; Berry 

 Lake, Cook Co. (Higley) ; sloughs of Winnebago Co. (Hinkley; Walker) ; 

 Will Co. (Marsh) ; Cedar Lake, Lake Co.; northern Illinois (State Laboratory) ; 

 Aledo, Mercer Co. (Walker). 



Indiana: George Lake, Lake Co. (Woodruff). 



Iowa: Iowa River (Dall) ; Dallas Co.; Des Moines, Polk Co.; Burling- 

 ton, Des Moines Co. (Keyes) ; pond near West Liberty, Muscatine Co.; north 

 of Iowa City, Johnson Co. (Pilsbry) ; Spirit Lake, Dickinson Co.; Algona, Kos- 

 suth Co. (Shimek) ; Davenport, Scott Co. (Tryon) ; vicinity of Des Moines 

 (Van Hyning) ; Boone Co.; Iowa River (Walker); Muscatine, Muscatine Co. 

 (Witter). 



Kansas: Lake Farland, McPherson Co. (Call; Cragin). 



Michigan: In small lake, Antrim Co. (Walker). 



Minnesota: Elk River, Sherburne Co. (Bailey); Lake Minnetonka, Hen- 

 nepin Co. (Cope) ; Minneapolis, Hennepin Co. (Hemphill) ; Lake Albert Lea, 

 Freborn Co. (Hemphill; Walker); Pelican Lake, Crow Wing Co. (Nason) ; 

 Belle Lake, Wright Co. (Sargent) ; Lake Calhoun, Hennepin Co. (Walker). 



Ohio: Cincinnati, Hamilton Co. (Allan; Anthony; Lee; Shaffer) ; Poland, 

 Mahoning Co. (Kirtland; Lea; Walker); pond near Congress Lake, Stark Co. 

 (Walker). 



Wisconsin: Milwaukee, Milwaukee Co. (Lapham) ; East River, Green 

 Bay and DePere, Brown Co. (Marston; Wis. Nat. Hist. Surv.) ; Fox River and 

 Green Bay (Walker). 



Geological Distribution : Unknown. 



Ecology : Exilis is an inhabitant of sloughs, ponds and rivers 

 which dry up more or less during a portion of the year. 



Remarks : This very characteristic and usually very distinct spe- 

 cies is a common Lymnaea in the Upper Mississippi Valley streams 

 and ponds. Its most pronounced distinguishing features are the long, 



