AMERICAN SPECIES OP VERTIGO. 93 



pression on the back over it ; 6 teeth ; 1.7 x 0.95 mm. 

 Maine. V. nylanderi, no. 11. 



Lower palatal fold not notably immersed. 6. 



6. Shell sharply but very finely striate, especially the penult 

 whorl ; no palatal callus ; 1.85 to 1.95 x 1 mm. ; 5 to 6 

 teeth. V. gouldii, no. 10. 

 Shell nearly smooth, or but weakly striate. 7. 



7. Crest and palatal callus moderately or strongly de- 

 veloped. 8. 

 Crest very low when present ; palatal callus very weak 

 or wanting 1 . 11. 



8. Shell cylindric-oval, 1.8 to 2 mm. long ; no angular lamella 

 and the basal fold small or wanting. Maine to Va., 

 west to Lake Superior. V. pygmcea, no. 9. 

 Ovate, 1.8 to 2.2 mm. long. 9. 



9. No angular lamella or basal fold; upper palatal fold 

 small or minute. 10. 

 A basal fold, and often an angular also ; ovate-conic ; 

 upper palatal fold well developed. Northern states. 



V. v. elatior, no. 8a 



10. Palatal callus moderate or thin ; Maine to Colo. 



V. tridentata, no. 16. 

 Palatal callus heavy ; Bermuda. V. marki, no. 17. 



11. Angular, parietal and columellar lamellae, upper and 

 lower palatal folds ; no crest ; 1.25 x 0.84 mm. Florida 

 Keys. V. hebardi, no. 13. 

 No angular lamella, 4-5 teeth, a basal fold present or 

 wanting; Northern States and Canada. 12. 



12. 1.75 x 1.1 mm. V. ventricosa, no. 8. 

 1.5 x 0.9 mm. V. bollesiana, no. 12. 



(West Coast species). 



1. With 4 or more well developed teeth. 



With 2 or 3 weak teeth; no trace of crest or palatal 

 callus ; 2 x 1.23 mm. ; California. V. sterkii, no. 20. 



2. 4 teeth; cylindric-oval; Oregon to Alaska. 



V. columbiana, no. 18. 

 5 to 6 teeth. 3. 



