MOLLUSCA OF MICHIGAN— WALKEIr. 



513 



the parietal is the largest, the columellar next and the inferior palatal third 

 in size; parietal and inferior palatal straight. 



Alt. 2, diam. 1 mm. 

 Pupa tappaniana, C. B. Adams, Thomp. Hist, of Vt., 158, (1842). 



pentodon, W. G. Binney, Man. Am. Land Shells, 323, fig. 348, 



(1885). 



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



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



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



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



Distribution probably the same as that of B. pentodon. This species and 

 pentodon are distinguished by the ridge of callus within the lip on which the 

 lamellae are situated. Heretofore usually known as B. pentodon Say. But 

 Say's species is that commonly called B. curvidens Old. 



Pupilla 

 Pupa 



Genus PUPILLA Leach. 



Shell deeply rimate or perforate, cylindrically shortened, apex extended 

 into an obtuse cone, horn-colored, smooth; whorls 5-9; aperture rounded 

 with few or no folds; peristome somewhat expanded. 



Animal heliciform, small, short, blunt before, tapering 

 behind; mantle posterior, thin, protected by a shell; res- 

 piratory and anal orifices on the right side of the mantle, 

 under the peristome of the shell; generative orifice be- 

 ^ . Fig. 137. hind the right eye-peduncle; eye-peduncles long; tentacles 



Animal of p. muscoruw , , t_x ii i x- 



(Biimey.) " stout. Very short; no caudal mucus pore or locomotive 

 disk. 



Jaw slightly arched, concave edge waved. 



Lingual band narrow, central teeth tricuspid, laterals bicuspid, uncini 

 serrated. 



Fig. 138. Jaw of P. muscorum. (Binney.) Fig. 139. Dentition of P. muscorum. (Binney.) 



PUPILLA MUSCORUM (LinEeus.) 



Fig. 140. 

 P. muscorum. (Morse.) X5. 



Fig. 141. 

 Var. unidentata. (Morse.) 



Fig. 142. 

 Var. biaranata. 



Shell perforate, sub-cylindrical, apex obtuse, dark chestnut color; whorls 

 6-7, rounded, finely striate; suture deep; aperture nearly circular, small, 

 thickened internally, edentulous; peristome thin, sharp, ^ith a thick, white 

 exterior rib slightly behind it. 



