AMERICAN SPECIES OF 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. 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. pygm&a, 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. trident at a, 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. 2. 

 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. 



