MOLLUSCA OF MICHIGAN— WALKER. 



481 



VITREA nULTlDENTATA (Binney). 



Shell iimbilicated, depressed, flattened above, very thin, 

 pellucid; yellowish horn-cobr, shining; whorls 6, narrow, 

 slightly convex, slowly increasing in diameter, very closely 

 ribbed striate above, beneath smoother; suture impressed; 

 aperture narrow extending to the umbilicus; peristome acute; 

 umbihcus very small, rounded; base convex, indented around 

 the umbilicus; two or more rows of very minute white teeth 

 radiating from the umbihcus on the base of the last whorl. 

 Fis.oi.G.muUidentata Alt. 1^. greater diam. 3^ mm. 



(Binney.) X-i.7. 



Helix vndtidentata, Binnev, Bost. Jour. Xat. Hist.. III., 425, pi. 



XXII.. fig. 5. (1840). 

 Zonites multidentatus , W. G. Binnev. Man. Am. Land Shells, 183, fig. 



180, (1885). 

 Gastrodonta multidentata . Currier. Shell-bearing Moll. Mich., 4. (1868.) 



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



Zonites 



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



Rare and local. It has been found in Marquette. Ontonagon, Emmet. 

 Grand Traverse. Benzie, Iosco. Saginaw, and Kalamazoo counties, which 

 indicates a general distribution throughout the state. 



Genus EUCONULUS Reinhardt. 



Shell imperforate or very narrowh' perforate, turbinate, arcti-spiral ; 



whorls 5-6, rather convex; aperture depressed-lunar; the penultimate whorl 



strongly excided, somewhat obliciue. Peristome with margins separated. 



Animal bluish-black on the head, neck and eye peduncles, hghter on the 



sides and base; foot very narrow, threadlike, a cUstinct 



caudal mucus-pore. 



Jaw arcuate, ends attenuated; anterior surface smooth, 

 Fi<'5i concave, margin smooth, with an obtuse median pror 



Jaw of jjifconuzws (Binney.) jection. Dentition as usual in the family, but is peculia 

 in the bifurcation of all the maroinal teeth. 



)2. Dentition of Euconulus. (Binney.) 



KEY TO THE SPECIES OF EUCOXULUS. 



I. Whorls 5 or less, T\ider and spire less elevated than in II., the peri- 

 pheral angle in middle of whorl fidvus. 



II. Whorls 6, very narrow, spire more elevated, peripheral angle above 

 the middle of the whorl chersinus polygyratus. 



