MOLLUSCA OF MICHIGAN— WALKER. 443 



Vitrina limpida Gld. Pyramidula asteriscus (Mse). 



Vitrea hinneyana (Mse). Vertigo gouldii Binn. 



Vitrea jerrea (Mse). Vertigo bollesiana (Mse). 



Vitrea multidentata (Say). Vertigo ventricosa (Mse). 



Zonitoides exigua (Stimp). Cochlicopa luhrica (Mull). 



Acanthinula harpa (Say). Sphyradium edentulum (Drap). 



Five of these have apparently a general distribution over the state, viz.: 

 Vitrea midtidentata (Say). Cochlicopa luhrica (Mull). 



Vertigo gouldii Binn. Sphyradium edentulum (Drap). 



Vertigo ventricosa (Mse). 



Vitrea hinneyana (Mse). and Zonitoides exigua (Stimp.) have both been 

 reported from Kent county. This, however, is the only locality reported 

 for either of these species south of the line of Wexford and Iosco counties. 

 Vitrea jerrea has been found in Gratiot county. With these exceptions, 

 the remaining five boreal species have thus far been found only in the north- 

 ern counties of the lower peninsula and in the upper peninsula. That is a 

 distribution agreeing substantially with the delineation of the boreal region 

 by Merriam. 



Two species, Vitrea cellaria and Agriolimax agrestis are European species 

 which have been locally introduced in recent years. 



The remaining fifty-five species comprised in our fauna, belong to the In- 

 terior Region of Binney, which corresponds substantially with the Transition 

 and Upper Austral Life Zones as established by Merriam. Of these, twenty- 

 six species have a general distribution, at least as far north as the eastern 

 extremity of the upper peninsula. One, Polygyra sayana (Pils.), is appar- 

 ently restricted to the northern part of the lower peninsula, but on the east 

 coast comes down as far south as Tuscola and Huron counties. Another, 

 Pallifera dorsalis, has only been found as yet, in Marquette county and 

 Isle Royale; while the remaining twenty-seven species have not, as yet, 

 been reported from north of the Saginaw-Grand valley, except Polygyra 

 monodon and Gastrodonta intertexta, which range northeasterly into the 

 ''Thumb" (Huron, Tuscola and Sanilac counties); and Omphalina inornata, 

 which has been reported from Oceana county. 



Of the thirty-two species given by Binney as of the Northern Region, 

 eight are peculiar to Greenland and Alaska. Of the remaining twenty-four, 

 twenty have been found in Michigan. While of the sixty-nine species be- 

 longing to the Interior Region fifty-three are known to inhabit this state. 

 That is of seventy-two Michigan species, twenty, or a little more than one- 

 third belong to the northern fauna and fifty-three to the interior fauna. 

 The addition of the few species not included in Binney's list would not per- 

 ceptibly change the proportion. This is what would be naturally expected 

 from the position of the state upon the northern border of the Interior Region 

 and its very considerable longitudinal extent. 



The eighty-one species included in the present catalogues are divided 

 among twelve families and twenty-five genera as follows: 

 41 



