126 AMERICAN SPECIES OF VERTIGO. 



Island! Uiialaska! Booluk Island, Unalga Pass! Akutaii 

 Island! Popof Island, Shumagins, St. Paul, Kadiak Island! 

 Orca, Prince William Sound! Yakutat Bay! Berg Inlet, 

 Glacier Bay ! Muir Inlet !). Pupa decora GOULD, Proc. Boston 

 Soc. N. H. ii, 1848, p. 263, fig. in text (region of Lake Su- 

 perior) . BINNEY, Terr. Moll, v, 1878, p. 201, pi. 71, f. 3 

 (Fort Resolution, Great Slave Lake). Vertigo decora Gld., 

 MORSE, Amer. Naturalist i, 1868, p. 670 (Ascutney, Vt., L. L. 

 Thaxter] . REINHARDT, S. B. Ges. Nat. Freunde, Berlin, 1883, 

 p. 39 (Portage Bay, Killisnoo, Katlrachia, Kluguan, lower 

 Deja valley and on Pyramid Island, Krause). 



An imperforate cylindric-oblong or somewhat ovate shell, 

 with short, rather small teeth arranged in form of a cross, 

 or not infrequently the upper palatal fold is wanting, es- 

 pecially in examples from the loess of Iowa. It is widely 

 distributed in the Dominion of Canada and Alaska, and in 

 the loess formation of Iowa and Kansas. 



V. modesta differs from typical V. m. corpulenta by the 

 more cylindric shell, with one whorl more, but intermediate 

 individuals or lots occur in the West. No specimens having 

 a distinct angular lamella are known from east of the Rocky 

 Mountains. 



There are numerous forms and mutations, some of them 

 apparently subspecies characteristic of definite areas; others, 

 such as parietalis, often occur associated with various races 

 in the same colonies. The subspecific taxonomy is more or 

 less arbitrary, and the number of forms worth recognition 

 by name will vary with the material studied and the observer 

 until collections fairly covering the range of the species are 

 available. 



"This is the most abundant and widely distributed species 

 in the north country." The type locality of modesta was 

 somewhere near or west of the western end of Lake Superior. 

 P. decora also came from the region of Lake Superior. The 

 two names were evidently applied to exactly the same race. 

 A photographic copy of Gould's figure of P. decora is given 

 on p. 124, fig. 1. 



It is a variable snail. A specimen from Labrador meas- 



