518 



MICHIGAN SURVEY, 1905. 



VERTIGO BOLLESIANA (Morse) 



Shell perforate, cylindrical-oVate, delicately striate? 

 light horn-color; apex obtuse; whorls four, subconvex; 

 suture well impressed; aperture sub-orbicular, some- 

 what flattened on its outer edge but not indented; 

 lamellae five, one parietal, two columellar and two 

 slightly elevated, lamelliform, within and at the base; 

 Fig. 152. V. boiiesiana. (Morse.) peristome subreflected and thickened. 



Alt. If, diam. J mm. 

 Isthmia boiiesiana, Morse, Ann. N. Y. Lye, VIII., 209, fig. 4-6, (1865). 



Vertigo — , W. G. Binney, Man. Am. Land Shells, 191, fig. 193, (1885). 



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



Rare in Michigan. Petoskey, Charlevoix, Crystal Lake, Benzie county^ 

 and Huron mountain, Marquette county, are the only localities reported. 



Distinguished by its flattened, not incurved, outer lip, and lamellar teeth 

 on base of aperture. 



VERTIGO TRIDENTATA Wolf. 



Shell narrowly ovate, amber-colored, highly 

 polished; whorls five, rather convex, smooth, 

 apex obtuse; suture impressed; aperture very 

 slightly thickened within, apertural lamellae 

 typically three, one parietal, one columellar 

 and one palatal, forming a regular triangle, a 

 very minute upper palatal is occasionally 

 present. 

 Fig. 153. v.tridcntata. x 16. Alt. 1.66, diam. 1.1 mill. 



Vertigo tridentata, Wolf, Am. Jour. Con., V., 198, pi. XVII., fig. 1, (1870). 



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



Apparently rare, but probably overlooked on account of its size. Ann 

 Arbor and Grand Rapids are the only localities thus far reported. A well 

 marked species characterized by its regularly ovate outline, few and small 

 apertural lamellae and very slight internal thickening of the outer lip. The 

 figure of the aperture is copied from that of Sterki. 



Family COCHLICOPID^E. 



Shell oblong, cylindric-oblong or narrowl}^ tapering, smooth and glossy, 

 with imperforate axis; aperture ovate or acuminate, the columella notched 

 below or continuous with the basal Up. Foot without pedal grooves. Kid- 

 ney with direct ureter, of the Basommatophorus type. Genitalia with a long 

 appendix on the penis. 



Jaw vertically striate, thin, arcuate. 



Radula with central tooth small, tricuspid; central cusp long and narrow; 

 side cusps of subequal length; laterals bicuspid; marginal teeth low, wide, 

 multidentate. 



Genus COCHLICOPA (Fer.) Risso. 



Shell ovate-oblong, imperforate, smooth, pellucid, glistening, dark horn- 

 colored; whorls rather convex; aperture less than half the shell's lengthy 



