MOLLUSCA OF MICHIGAN— WALKER. 



485 



Alt. 2.D, diam. 5.5 mm. 

 Helix limatula, Ward, Bost. Jour. Nat. Hist., III., 434, pi. XXL, 



fig. 2, (1840). 

 Zonites limatulus, W. G. Binney, Man. Am. Land Shells, 220, fig. 233, 



(1885). 

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



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



, DeCamp, Shell-bearing Moll. Mich., 5, (1881). 



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



This is apparently one of the rarest of Michigan species. None of the 

 citations have been authenticated, and several of them have been proven 

 to be erroneous. A single specimen in the collection of Mr. L. H. Streng, 

 from Grand Rapids, is the only Michigan example that has thus far passed 

 under observation. It is easily distinguished by its color, wide umbilicus 

 and striate surface. 



ZONITOIDES MINUSCULA (Binney). 



Shell umbilicated, minute, depressed convex; whitish; whorls 4, 

 convex, slowly increasing in diameter, very finely striate; suture 

 deep; aperture nearly circular; peristome thin, acute; umbilicus 

 large, deep and exhibiting the volutions; base rounded. 

 z.mmuscuia. Alt. 1, greater diam. 2^, lesser 2 J mm. 



(Binney.) 



minuscula, Binney, Bost. Jour. Nat. Hist., III., 435, pi. 



XXII. , fig. 4, (1840). 

 minusculus, W. G. Binney, Man. Am. Land Shells, 63, fig. 



18, (1885). 

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



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



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



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



Common and of general distribution in the lower peninsula. Has not yet 

 been reported from the upper peninsula. A w^ell marked little species, char- 

 acterized by its depressed form^and large umbihcus. 



Helix 



Zonites 



Helix 



Pseudohyalina 



Fig. 61. 



Z. exigua. x6.4. 



(Binney.) 



ZONITOIDES EXIGUA (Stimpson). 



Shell broadly umbilicated, depressed, pellucid, greenish 

 horn-color, spirally striate and with distant longitudinal 

 oblique ribs; spire very low; apex smooth; whorls 3^, convex, 

 the last rounded; aperture oblique, transversely rounded, re- 

 mote from the axis; peristome simple, acute. 

 Alt. Yj greater diam. 2\ mm. 

 Helix exigua, Stimpson, Proc. B. S. N. H., III., 175, (1850). 



Zonites exiguus, W. G. Binney, Man. Am. Land Shells, 181, fig. 177, 



(1885). 

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



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



Zonites exiguus, Wa^lker, R^v. Moll. Fauna Mich., 16,(1894). 



