MOLLUSCA OF MICHIGAN— WALKER. 403 



N. 8. P. 1894, 20, pi. L, 



Polygyra tridentata fraudulenta Pilsbry, Proc. A 



%. 6. 



Triodopsis fallax, 

 Helix 



W. G. Binnev, Man. Am. Land Shells, 292, 



fig. 314, (1885). 

 Sager, Doc. H. Rep. Mich., 1839, 420, sep- 

 arate 14. 

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

 Currier, Shell-bearing Moll. Mich. ,6, (1868). 

 DeCamp, Shell-bearing Moll. Mich., 7, 



(1881). 

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

 More abundant than the preceding species. Distribution the same. 

 This species is frequently confounded with P. tridentata, but is very dis- 

 tinct and can be easily separated by its basin-shaped aperture and the larger 

 size of the superior labial tooth. 



Triodopsis , 



Polygyra fraudidenta, 



POLYGYRA INFLECTA (Say) 



Shell imperforate, depressed, epidermis brownish horn- 

 color; very finely hirsute; whorls with very minute trans- 

 verse striae; suture not much impressed; aperture tri- 

 lobed, very much contracted behind the lip; peristome 

 white, narrow, reflected, not projecting beyond the con- 

 Fig.8. p.infleda. (Bmney)^^^^ ^^ ^^^ ^^^^ ^^^^^^. ^^^ ^^^ ^^^^^ margin of the peri- 

 stome are two acute teeth, with the points directed inwards, one near the 

 base, the other midway between that and the junction of the peristome and 

 the body whorl, with a circular sinus between them; parietal wall with a long 

 arcuated, white tooth. Alt. 6f, greater diam. 12, lesser 11 mm. 

 Helix inflecta, Say, Jour. A. N. S. P. II., 153, (1821). 



Triodopsis , W. G. Binney, Man. Am. Land Shells, 289, fig. 310, 



(1885). 



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



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



Isognomostoma , Currier, Shell-bearing Moll. Mich., 6, (1868). 



, DeCamp, Shell-bearing Moll. Mich., 7, (1881). 



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



Quite rare. Kent, Washtenaw, Wayne and Monroe counties. Distin- 

 guished from the other tridentate species by its small size and imperforate 

 base. 



POLYGYRA PROFUNDA (Say) 



Shell broadly umbiHcated, orbicularly depressed; 

 yellowish horn-colorecl, with reddish brown revolving 

 lines and bands; whorls 5, convex, obliquely striated; 

 suture distinct; aperture almost circular, its extremi- 

 ties converging, flattened towards the plane of the base; 

 peristome white, thickened, reflected, with an obtuse 

 tooth on the basal edge ; umbilicus rather large and pro- 

 found; base convex. Alt. 14, greater diam. 29, lesser 

 27 mm. 



Helix profunda, 'Say, Jour. A. N. S. P. II, 160, (1821). 



Mesodon profundus, W. G. Binney, Man. Am. Land Shells, 318, fig. 342, 

 (1885). 



Fig. 9. Polygyra profunda. 

 (Binney.) 



