144 AMERICAN SPECIES OF VERTIGO. 



Pupa rowelln NEWCOMB, Ann. Lyceum of Nat. Hist. N. Y., 

 vii, April, 1860, p. 146. BLAND, Ann. Lye. viii, p. 166, fig. 11. 

 -W. G. BINNEY, Terr. Moll, v, 1878, p. 202, fig. 106 (near 

 Oakland, Monterey, San Bernardino, El Dorado Co.) ; Man. 

 Amer. L. Shells, p. 483 (Alameda Co.). Vertigo (Nearctula) 

 rowelli Newc., STERKI, Nautilus vi, 1892, p. 5. 



With the teeth like V. califomica, this species differs by 

 its smoother surface. Under a lens there are delicate, irregu- 

 larly spaced thread-like striae corresponding to the far stronger 

 riblets of V. califomica. The color is somewhat brownish 

 olive. Specimens from Douglas county, Oregon measure: 



Length 2.7, diam. 1.5 mm. 



Length 2.65, diam. 1.35 mm. 



A single example was found in a lot of V. a. sanbernardi- 

 nensis from the San Bernardino Mts. It measures 2.48 x 

 1.35 mm. 



Subgenus VERTILLARIA n. subg. 



Shell oblong, with the columellar lamella in form of a blunt 

 vertical plate, other teeth short; outer lip biarcuate. In the 

 type species there is no angular lamella or basal fold, and 

 the upper palatal fold is minute or wanting. 



Type V. oscariana. Austroriparian, from Florida to Texas. 



The blunt, vertical columellar lamella, parallel to the axis, 

 is entirely unlike other American species of Vertigo, being 

 comparable to that of Vertilla angustior. I suspect Vertilla 

 may be the most nearly related form, though the American 

 species has the lower palatal fold much larger than the upper, 

 and there is no angular lamella. The deep external furrow 

 of the last whorl suggests that an ancestral form had a long 

 lower palatal fold, though the present species is rather de- 

 generate in teeth. There is no external crest and no palatal 

 callus. 



31. VERTIGO OSCARIANA Sterki. PL 8, figs. 8, 10, 11. 



"This is the most peculiar of our species. It is the size of 

 milium, but oblong with either end nearly equally pointed, 

 the last whorl being considerably narrowed and flattened to- 



