138 AMERICAN SPECIES OF VERTIGO. 



Length 2.1, diam. 1.35 mm. 



California: near Clear Lake, Lake Co., Hemphill. 



Pupa dalliana STERKI, Nautilus iv, June, 1890, p. 19 ; Au- 

 gust, 1890, p. 39, pi. 1, f. 2. W. G. BINNEY, Fourth Suppl. 

 Terr. Moll, v, in Bull. Mus. Comp. Zool. xxii, 1892, p. 195, fig. 

 in text. Vertigo (Haplopupa) dalliana Sterki, PILSBRY, 

 Nautilus xi, 1908, p. 119. 



"The specimens before me were fifteen, fresh, remarkably 

 uniform in their whole appearance ; all were more or less cov- 

 ered with a dark brown, hard crust of slime and dirt, generally 

 thickest around the aperture. Doubtless this coating is done 

 'purposely' by the animals, as in many other species also. 

 When cleaned, it shows about the size and shape of a well- 

 grown Vertigo ovata, Say, but by a good eye or under a glass 

 is at once recognized as something else, by the rounded aper- 

 ture and the absence of lamellae" (Sterki). 



The color is grayish-olive. There is a deep and rather long 

 crevice but no umbilical perforation. It resembles V. m. occi- 

 dentalis closely in shape, but is slightly smaller, greener in 

 hue, and toothless. V. m. castanea has a more oval, less conic 

 shape. V. dalliana is perhaps a toothless member of the V. 

 modesta group, the end product of a tooth-degeneration series. 

 In the modesta and calif ornica groups there are many forms 

 showing various stages of this process. - V. m. occidentalis ap- 

 pears to be the most nearly related species. 



By a typographical or other error the length was given as 

 1.2 mm. instead of 2.1, in the original description. The type 

 specimen is here figured, no. 416 Sterki collection. 



Group of Vertigo calif ornica. 



Nearctula STERKI, Nautilus vi, 1892, p. 5, type V. calif ornica. 



Vertigines of cylindric shape, without crest or grooves over 

 the palatal folds, and with no palatal callus ; typically having 

 parietal and columellar lamellae, upper and lower palatal 

 folds, but in some forms the teeth have been partly lost, only 

 the parietal remaining, or sometimes the aperture is wholly 

 toothless. 



These forms are approached so closely by some of the 



