MOLLUSCA OF MICHIGAN— WALKER. 



479 



VITREA BINNEYANA (Morse). 



Shell broadly iimbilicated, subglobosc, transparent, al- 

 most colorless, shining, smooth, with microscopic wrinkles 

 of growth and still more delicate, oblic[iie wrinkles; spire 

 Fig 44 V binneyana l^^^ ^^'^^}^^ elevated; whorls about 4, rounded, gradually 

 (Binney.) increasing, the last globose; aperture oblique, subcircular, 



large; peristome simple, acute. 



Alt. 2, cliam. 4 mm. 

 Hyalina binneyana, Morse, Jour. Portl. X. H. Soc, I., 13, fig. 25-6, (1864). 

 Zonites hinneyanus, W. G. Binnev, Man. Am. Land Shells, 180, fig. 174, (1885). 

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



A northern species of general distribution north of Iosco county. It has 

 also been reported from Kent county. Easily distinguished by its open 

 umbilicus, smooth surface and white color. 



Section STRIATURA Morse. 



Shell small, striate, reticulated with 

 impressed, spiral lines, thin, translu- 

 cent, without teeth in the aperture. 



Jaw almost smooth, with a median 

 furrow and notch; central tooth of ra- 

 dula very large. 



Fig. 45. Jaw of Y. ferrea. (Biiiney.) 



F-g. 4j. Dentition of V. ferrea. (Bumcy.) 



VITREA FERREA (Morse). 



Shell umbilicated, depressed-globose; transparent, of a 



light steel-gray color, not shining, marked with very deh- 



cate incremental wrinkles and microscopic revolving lines; 



^" (Binney.)^^"' reticulatiug the surface; spire slightly elevated; whorls 3, the 



last rapidly enlarging, globose; suture distinct and deeply channeled near 



the apex; aperture large, transversely subcircular; peristome simple, acute, 



its extremities not approaching, that of the columella scarcely subreflected . 



Alt. Ij, greater diam. 2^ mm. 

 Striatura ferrea, Morse, Jour. Portl. N. H. Soc, I., 17, figs. 36-40,^(1864). 

 Zonites ferreus, W. G. Binney, Man. Am. Land Shells, 181, fig. 175, (1885). 

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



A northern species of general distribution. Gratiot county is the most 

 southerly locality reported. The characteristic sculpture of the surface can 

 be seen only with the microscope. 



