MOLLUSCA OF MICHIGAN— WALKER. 



521 



Helix pulchella, Muller, Verm. Hist., II., 30, (1774). 



Vallonia 



Helix 



Vallonia minuta. 



W. G. Binney, Man. Am. Land Shells, 77, fig. 39, (1885), 

 Miles, Rep. Geol. Surv. Mich., 236, (1861). 

 Currier, Shell-bearing Moll. Mich., 5, (1868). 



, DeCamp, Shell-bearing Moll. Mich., 6, (1881). 



pulchella, Walker, Rev. Moll. Fauna Mich., 17, (1894). 



Common and of general distribution in the lower peninsula. Not yet 

 reported from the upper peninsula, except on Isle Royale. 



The Vallonice are easily distinguished from the other genera represented 

 in our fauna by their small size and strongly reflected white lip. The regu- 

 lar rounded umbilicus and scarcely expanded body-whorl are very charac- 

 teristic of this species, and w^hen typical, it can easily be separated from V, 

 excentrica, but occasional examples are often difficult to determine. 



VALLONIA EXCENTRICA Sterki. 



Shell moderately umbilicated, the umbilicus elon- 

 gate; slightly convex above, pale horn colored; trans- 

 parent or slightly opaque, smooth or very finely and 

 irregularly striate, whorls S-3^; the last comparatively 

 large, well rounded, expanding toward the aperture; 

 suture moderately deep; aperture nearly circular, sub- 

 angular at the base, the umbilical margin somewhat 

 protracted; peristome everted only in the inferior part, 

 with a strong white lip, shining through the shell. 



Alt. 1.1, greater diam. 2.3, lesser 1.8 mm. 



Fig. 161. V. excentrica. 

 (Sterki.) XIO. 



Vallonia excentrica, Sterki, Man. Con., VIII., p. 249, pi. 32, fig. 6-9, (1893). 

 ^ Walker, Rev. Moll. Fauna Mich., 17, (1894). 



Apparently of general distribution in the southern part of the lower pen- 

 insula. Not yet reported north of Newaygo county. Typically easily dis- 

 tinguished by the peculiar shape of the umbilicus and the expanded form 

 of the last whorl toward the aperture. 



VALLONIA COSTATA (Muller). 



Shell moderately umbilicated, depressed, convex above^ 

 or nearly flat; grayish to light or reddish horn-colored; 

 with rather regularly set, membranous ribs and finer 

 striae between them; whorls 3^, at the circumference 

 somewhat angular, with a deep suture; the last whorl 

 expanding to the aperture, sharply and moderately de- 

 scending in front; aperture almost circular, a little flat- 

 tened above, peristome strongly and abruptly everted 

 with a strong white Hp. 



Alt. 1.1, greater diam. 2.5, lesser 2.1 mm. 



Fig. 162. V. costafa. 

 (Sterki.) XIO. 



Helix costata, Muller, Verm. Hist., II., 31, (1774). 



Vallonia , Walker, Rev. Moll. Fauna Mich., 17, (1894). 



Rare in Michigan. Owosso, Shiawassee county, Isle Royale and Monroe 

 are the only recorded localities. 



