AMERICAN SPECIES OP VERTIGO. 105 



15. VERTIGO PARVULA Sterki. PI. 12, figs. 7, 9. 



"It is of about the size, shape and appearance of V. (Angus- 

 tula} milium Gld., but ranges in quite another group, having 

 a quite simple palatal wall and margin, and only 3 lamellae" 

 (Sterki). 



The shell is minute, subcylindric, tapering very little up- 

 wards, the summit obtuse ; thin, subtransparent, slightly yel- 

 lowish, smooth and glossy, becoming finely striate behind 

 the outer lip. The whorls are moderately convex, the last 

 whorl well rounded, slightly impressed behind the projection 

 of the outer lip. The aperture is somewhat triangular, with 

 three teeth : parietal lamella rather short and high ; columellar 

 lamella short, steeply ascending inwardly; lower palatal fold 

 rather high in front, rapidly becoming lower as it recedes, 

 penetrating to the dorsal side. Peristome very little everted, 

 slightly thickened, and having a distinct callus ridge within. 

 The outer lip projects forward and is slightly bent inward 

 above the middle. 



Length 1.55, diam. 0.85 mm. ; barely 5 whorls. 



Ohio: Summit Co., A. Pettingell. Also found by A. G. 

 Wetherby in the mountains of North Carolina, according to 

 Dr. Sterki. 



V. [crtigo] parvula STERKI, Nautilus iii, April, 1890, p. 136. 



Figures and description are from the type specimen, no. 

 270 Sterki coll. It is one of the rarest species, known by the 

 small size, cylindric shape and three well-developed teeth, 

 the lower palatal being quite long and not marked externally 

 by an impression. The auricle or point of the outer lip pro- 

 jects well forward but is not much bent inward. 



It is much smaller than V. tridentata, and more cylindric 

 and lighter colored than V. perryi, with relatively larger teeth. 

 It is quite distinct from all of our species. 



The name parvula has been used in Pupa by Deshayes, 1864, 

 but as there is some doubt as to whether his species is a 

 Vertigo, I do not think it necessary to change the name of the 

 form under consideration. 



