MOLLUSCA OF MICHIGAN— WALKER. 



493 



PYRAMIDULA PERSPECTIVA (Say). 



Fig. 82. 



P. perspeciiva. 



(Binney.) 



Helix 

 Patula 



Shell broadly and perspectively umbilicated, orbicular, scarcely 

 convex, above, excavated below; thin, reddish horn-color, regu- 

 larly ribbed; whorls 6^, gradually increasing; aperture small, 

 lunately subcircular, with a single subprominent tooth on the 

 base of the shell near the columella; peristome simple, acute, its 

 extremities widely separated. 



Alt. 3, greater diam. 8, lesser 7^ mm. 



perspectiva, Say, Jour. A. N. S. P., I., 18, (1817). 



, W. G. Binney, Man. Am. Land Shells, 260, fig. 276, 



(1885). 



Helix ■ , Sager, Doc. H. Rep. Mich., 1839, 420, separate, 14. 



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



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



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



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



Generally distributed south of the Saginaw-Grand valley and northerly on 

 the western side of the state to the Grand Traverse region. Distinguished 

 from P. cronkhitei anthonyi by its greater size, coarser striae, wider umbilicus, 

 and the tooth within the aperture near the base of the columella. 



PYRAMIDULA CRONKHITEI ANTHONYI Pilsbry 



. "^ Shell widely umbilicated, orbicularly convex, thin, brownish horn-- 

 color; closely-ribbed striate; whorls 4, flattened above, rounded be- 

 low, the last rather wide, aperture sub-circular; peristome simple, 

 acute, its terminations approaching. 



Fig. 83. , Alt. 3, greater diam. 6, lesser 5^ mm. 



p. cronkhitei ' ° 



anthonyi. 

 (Binney.) 



Pyramidula cronkhitei anthonyi, Pilsbry Proc. A. N. S. P. 1906, 153. 

 Patula striatella, W. G. Binney, Man. Am. Land Shells, 69, 



fig. 28, (1885). 



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



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



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



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



Var. ALBINA "Morse," CkU. 



Greenish white, otherwise similar to the type. 

 Patula striatella albina, ''Morse," Cockerell, Naut: III., 102, (1890). 

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



Var. CATSKILLENSIS (Pilsbry). 



Umbihcus wider and periphery distinctly angulated. 

 Pyramidula striatella catskillensis, Pilsbry, Naut. XII., 86, (1898.) 

 The typical form is very abundant in all parts of the lower peninsula. 

 Isle Royale being the only recorded locality in the upper peninsula. The 

 variety, albina, has been found only at Mackinac Island and Isle Royale. 



