110 AMERICAN SPECIES OF VERTIGO. 



Oregon : Douglas Co., F. H. Andrus, type loc. Also north- 

 ward, to Chehalis Co., Washington. 



Vertigo cmdrusiwna PILSBRY, Proc. A. N. S. Phila. 1899, 

 p. 315, fig. 3 ; Nautilus xvii, p. 131. 



It stands very near V. pygm&a, but is slightly longer, the 

 crest and palatal callus are less developed, and there is an 

 angular lamella in the most fully developed examples, which 

 however have the other teeth smaller than in pygnuea. 



The type specimen is redescribed above and drawn in pi. 

 11, fig. 10. In the original description and figure the angular 

 lamella was overlooked; the shell was rolled too far towards 

 the right under the monocular microscope used, and this small 

 tooth was not seen. 



There are ten shells in the original lot, but perhaps only 

 the type and another are absolutely mature. Both have the 

 angular and the basal teeth distinct. Two other shells are 

 very nearly adult. In both the angular lamella is represented 

 by a slight thickening, of the color of the shell, and only notice- 

 able in a basal view, and neither of them has a basal fold 

 (fig. 11). It is likely that the basal is either wanting or 

 present in adult examples of the species. 



Similar specimens were taken by Mr. S. S. Berry at Lake 

 Quinault, Chehalis Co., Washington ; one before me has a very 

 low angular lamella but no basal fold. The spire has whitish 

 streaks. 



A series of some thousands of specimens was taken by Mr. 

 John A. Allen "about clumps of bushes in a meadow," 

 Oswego, Clackamas Co., Oregon. The shells (pi. 11, fig. 9) are 

 all smaller than the type lot, variable in size and shape, and 

 with the crest weak, or in the shorter individuals wanting. 

 Among many examined, none has an angular lamella. The 

 basal fold is occasionally developed, but more frequently 

 absent. There is a distinct if thin palatal callus except in 

 the quite small individuals. The color is usually darker than 

 cinnamon brown or russet, often with light streaks on the spire. 



Length 2.15, diam. 1.2 mm. ; 514 whorls. 



Length 1.85, diam. 1.2 mm. ; 4% whorls. 



While this form has characters of V. columbiana, V. pygmtea 



