92 AMERICAN SPECIES OF VERTIGO. 



413, pi. 36, f. 6. VERRILL, Trans. Conn. Acad. xii, 1907, p. 

 170, f. 54c. 



While highly specialized and peculiar, this species appears 

 to be somewhat related to V. oralis and especially V. 

 alabamcnsis. It has also some resemblance but probably no 

 direct relationship to V. ova-ta. It differs from all American 

 species by the far more massive crest. There is a long lower 

 palatal fold, but it is not turned down at the end as in 

 V. milium, and the shape of the columellar lamella shows 

 that V. numellata is not an Angustula. 



This species was described from fossil examples in the lime 

 rock, but it is abundant as a recent shell in Paynter's Vale, 

 about Church Cave, near Tucker's Town. Except in color, 

 there is no difference between recent and fossil examples. 



Group of Vertigo pygmaea. 



It is scarcely possible to define this group, some species 

 approaching the group of V. ovata closely, while others are 

 hardly distinguishable from the modcsta group. As a whole 

 the group is equivalent to the European group of V. 

 moulinsicma and pygmaea. 



Key to species. 



(Eastern and central species). 



1. Aperture having 3 teeth, parietal, columellar and lower 

 palatal ; sometimes a minute upper palatal. 2. 

 Aperture having at least 4 well developed teeth. 5. 



2. 1.8 to 2.2 mm. long; upper palatal fold generally present 

 but minute. 3. 

 1.5 to 1.6 mm. long ; upper palatal fold rarely developed. 4. 



3. Palatal callus slight or wanting; Maine to Colorado. 



V. tridentata, no. 16. 

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



4. Subcylindric, yellowish, the lower palatal fold penetrat- 

 ing to the dorsal side ; Ohio, N. C. V. parvula, no. 15. 

 Ovate, dark olive buff, fragile, the lamella and folds small 

 and short. New England. V. perryi, no. 14. 



5. Lower palatal fold long, very deeply immersed, an im- 



