466 



MICHIGAN SURVEY, 1905. 



seem best to consider them simply as phases of one variety and to unite 

 them under the name having priority. 



P. albolahris rufa DeKay, cited by DeCamp, is simply a more deeply 

 colored form and is not entitled to varietal distinction. 



- POLYQYRA ZALETA (Binney). 



Shell imperforate, convex, somewhat ventricose; uni- 

 form yellowish horn or russet color; whorls 5-6, finely 

 and obliquely striate; body whorl large and ventricose; 

 suture well marked; aperture rounded; peristome thick- 

 ened, white, reflected; parietal wall with a prominent, 

 white, oblique tooth. 

 Fig. 14. p.zaieta. (Binney.) Alt. 17, greater diam. 28, lesser 23 mm. 

 Helix zaleta, Binney, Bost. Jour. Nat. Hist. I., 492, pi. xx, (1837). 

 Mesodon exoletus. W. G. Binnev, Man. Am. Land Shells, 39, fig. 331, (1885). 

 Helix zaleta, Sager Doc. H. Rep. Mich., 1839, 420, separate, 14. 



exoleta, Miles, Rep. Geol. Surv. Mich., 235, (1861). 



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



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

 Walker, Rev. Moll. Fauna Mich., 16, (1894). 



Polygyra 



Probably extends over the entire southern part of the state, although not 

 yet reported west of Saginaw, Ingham and Branch counties. The only records 

 north of the Saginaw-Grand valley are Osceola and Mackinac counties. 

 This species is frequently mistaken for the dentate form of P. albolahris or 

 vice-versa, and, indeed, in some cases it is not easy to tell from the shell 

 alone, where a given specimen belongs. In such cases a dissection of the 

 animal is necessary, as there are very distinct differences in the details of 

 the genitalia. Usually, however, the two forms can be separated without 

 difficulty, zaleta being much more ventricose and having a rounder aperture 

 than albolahris, which is more depressed, wider in proportion to its heighth, 

 and with the aperture wider and more flattened in the direction of the plane 

 of the base. Usually known as P. exoleta Binney, but zaleta has priorit}' 



4 POLYQYRA nULTILINEATA (Say). 



Shell imperforate, depressed, sub-globose; spire con- 

 vex; rather thin; yellowish brown, or russet color, with 

 numerous reddish, revolving bands; whorls 5-6, convex, 

 closely and obhquely striate, the last ventricose; suture 

 distinctly marked; aperture lunate; peristome white, 

 reflected, rather thin. 

 Fig. 15. p. muiHiineata. (Binney) Alt. 14, greater diam. 23, lesser 20 mm. 

 Helix multilineata, Say, Jour. A. N. S. P., II., 150, (1821). 

 Mesodon multilineatus , W. G. Binney, Man. Am. Land Shells, 302, fig. 323, 



(1885). 

 Sager, Doc. H. Rep. Mich., 1839, 420, separate, 14. 

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

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



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



Polygyra , Walker, Rev. Moll. Fauna Mich., 16, (1894). 



Helix midtilineata, 

 Mesodon — — , 



