AMERICAN SPECIES OF VERTIGO. 95 



it shows microscopic punctation or granulation. The basal 

 fold is usually quite small, though sometimes, as in the speci- 

 men from Prince Edward Island figured (fig. 1), it is well 

 developed. In many Maine examples it is absent (fig. 3, Buck- 

 field, Oxford Co., Me.). The degree of prominence of the in- 

 wardly bent point of the lip-edge varies a good deal. The 

 crest is quite low. Specimens measure : 



Length 1.7, diam. 1 mm.; 4y 2 whorls (Hebron, Me., fig. 2). 



Length 1.95, diam. 1.2 mm.; 4y 2 whorls (Brickfield, Me., 

 %. 3). 



A form which Dr. Sterki listed as V. approximans was 

 originally stated to be "characterized by the two palatal 

 lamellae being close together." It was from Rockford, 111. 

 The original specimens are lost, but what appears to be the 

 same form has been found in Ohio. " It is rather small, length 

 1.3, diam. 0.9 mm., more or less; short, slight, with no callus 

 in the palate or a slight one. There are parietal and colu- 

 mellar lamellae and two palatal folds, all small, the palatals 

 close" (Sterki). 



Dr. O. Boettger considered ventricosa a synonym of V. 

 monlinsiana of Europe (Jahrb. Nassauischen Vereins, 1889, 

 p. 307) ; but the resemblance does not appear sufficiently close 

 for specific identity. 



8a. Vertigo ventricosa elatior Sterki. PL 7, fig. 6. 



"Larger and more elevated than ventricosa, with a rather 

 acute apex ; a strong callus in the palate, into which the 

 palatal plicae merge, a strong tooth-like lamella in the base" 

 (Sterki). 



Length 2.15, diam. 1.2 mm. ; 5 whorls. 



New York, Ohio, Michigan and west to Montana (Sterki) ; 

 Aroostook and Hancock counties, Maine ; Darby and White 's 

 Springs, west of Ward, Mont. ; Field, B. C. and Laggan, 

 Alberta; Oscuro Mts., Socorro Co., N. M. 



Vertigo ventricosa var. elatior STERKI, The Land and 

 Fresh Water Mollusca in the vicinity of New Philadelphia ; a 

 contribution to the Natural History of Tuscarawas Co., Ohio, 

 p. 5, 1894. Eighth Ann. Rep. Ohio State Acad. Sci., 1900, p. 



