AMERICAN SPECIES OF VERTIGO. 85 



mentioned. In the Pacific states, there are specimens from 

 Seattle, Washington (P. B. Randolph) and Oswego, Clackamas 

 Co., northern Oregon (J. A. Allen). I have not seen it from 

 Idaho, Utah, Nevada or California, but allied or subspecific 

 forms occur in California. Specimens are also wanting in 

 this collection from the southern Atlantic states, from Virginia 

 to Florida. Antillean specimens are noted below. 



The Alaskan records are all from Dall. It appears to ex- 

 tend north to about 58, south to about 18. If the specimens 

 from these extremes are reliably determined, V. ovata has 

 the greatest range in latitude and climate of any Vertigo or 

 other Pupillid snail in the world, so far as I know. 



' ' V. antivertigo Drap. and V. ovata Say have almost exactly 

 the same dentition as to number, size, and shape, and places 

 of the single lamellae, and also as to other features of the 

 shells they are very similar. V. ovata, in general, is a little 

 larger, of lighter coloration, the margin is somewhat more ex- 

 panded; the aperture appears larger because the columellar 

 margin is relatively a trifle shorter; the whorls increase in 

 size somewhat more rapidly, and the suture is a trifle deeper. 

 Specimens from Massachusetts are not only of the same or 

 even a darker shade [than V. antivertigo], but also of the 

 same and sometimes of a smaller size, and other distinguish- 

 ing features are slightly marked. They resemble each other 

 so much that it is difficult to separate them, and if collected 

 at the same place no one would regard them as even distinct 

 varieties. I hesitate, however, to declare them identical be- 

 cause I have not yet made a comparison of the soft parts. 

 Doubtless they are parallel forms, and if found on the same 

 continent would be regarded as varieties of one species. 

 V. antivertigo is remarkably constant throughout Europe so 

 far as I know it, while V. ovata is on the contrary quite vari- 

 able, owing, possibly, to the greater differences in climate. 

 Also a few decided varieties exist and maybe more will be 

 found ; the future study of these forms is likely to be of great 

 interest" (Sterki). 



I have not seen var. antiquorum CklL, but no differential 

 characters of importance appear in the description, which 

 follows. 



