AMERICAN SPECIES OF VERTIGO. 123 



It may turn out that the slight differences in size and teeth 

 are insufficient for separating these forms specifically, and the 

 subordination of all under V. modesta would not surprise me, 

 when series of specimens from Lapland, Siberia, and Green- 

 land can be brought together for comparison with the better 

 known boreal American forms of V. modesta. 



Key to American species. 



Shell cylindric-oblong or cylindric-ovate ; to 5 teeth. 



V. modesta and allies, nos. 25-29. 

 V. rowelli, no. 32. 



Shell ovate, the spire strongly tapering ; California. 

 5 small teeth. V. occidentalis, no. 25/. 



Without teeth. V. dalliana, no. 30. 



25. VERTIGO MODESTA Say. PI. 10, figs. 1, 2; page 124, figs. 

 1, 2, 2a. 



"Shell dextral, suboval, minutely wrinkled; apex obtuse; 

 whorls six; umbilicus distinct; aperture obliquely subovate; 

 labium with a prominent compressed semioval tooth equidis- 

 tant from the extremities of the labrum, and a somewhat conic 

 one rather below the middle of the columella ; labrum not re- 

 flected, joining the preceding whorl at its upper extremity 

 with a curve; bidentate, lower tooth placed opposite to that 

 of the middle of the labium, the other smaller and placed a 

 little above. Length less than one-tenth of an inch. Inhabits 

 the Northwest Territory" (Say). 



The cylindric-oblong shell is from tawny to cinnamon 

 colored, glossy, rather weakly striate, the striation more dis- 

 tinct on the middle whorls. The last whorl has a weak crest 

 behind the obtuse, brown outer lip, which expands very little, 

 and is not noticeably caught in to form a sinulus. Teeth four, 

 white : the parietal and columellar lamellae and lower palatal 

 fold subequal, short; the upper palatal fold smaller. Length 

 2.6, diam. 1.3 mm. ; 5% whorls. 



Labrador, westward, over the crest of the Rocky Mts. 

 (Field, B. C.) to Victoria and Nanaimo. Reported locally 

 in Maine, Vermont and Connecticut. Loess of Iowa (Iowa 



