I'HE NAUTILUS. i 



cola Ingersoll is not even a true var. here, just as vai-. gredleri 

 Oessin on the old continent. The most beautiful specimens of 

 this formation I have seen are from Maine, in the collection of Mr. 

 Edw. S. Morse. 



4. This subgenus — in mss. for nearly two years — will be charac- 

 terized in another ai'ticle in the Nautilus. 



5. P. curvidens is very variable. The two extreme forms, gracilis 

 audfloridana, would unhesitatingly be regarded as widely distinct 

 species, if not connected by intermediate forms ; the latter comes 

 nearest P. pentodon, the former resembles some forms of P. hordea- 

 cella Pilsb. 



6. These species resemble the European forms so much in out- 

 line and general aspect that it seems best to range them in this 

 group or subgenus, although the apertural folds are much more 

 developed. 



7. The subgenus has been criticised by my esteemed friend, INIr. 

 Pilsbry* as being identical with Vertilla Moq.-Tand. If this were 

 the case, it would of course, be worse than useless. Vertilla was 

 established for the European Vert. 2nis ilia MiiW. and Ve7ietzii Charp. 

 {angustior Jeffr.), on account of their being sinistral. But the two 

 are quite different in structure, for while the former is simply a 

 Vertigo reversed, the latter, together with one similarly built, P. 

 (Vert), milium Gld., constitute a peculiar group, which I have 

 called Angustula, mainly characterized by the long and high gular 

 lamella and some other peculiarities. 



8. It is difficult to draw a limit between Pupa and Vertigo and 

 may prove to be impossible ; if so we will have to regard and 

 treat the latter as a subgenus of Pupa, as many prominent Euro- 

 pean conchologists do. And it appears more natural standing in a 

 line with Torquilla, Pupilla, Bifidaria, and its groups co-ordinate as 

 sections with those of the subgenera named. 



9. This interesting form has been detected in eastern Florida, 

 Volusia Co., by Messrs. Geo. W. and his son Oscar B. Webster, of 

 Lake Helen. These gentlemen spent several weeks in collecting 

 this and other small mollusca, making a trip of over a hundred 

 miles, and they first called my attention to this Vertigo. It is 

 decidedly different from rugosida in several points, and, as I have 

 seen no intermediate forms so fai', it may prove to be distinct. 



* Nautilus IIT, p. 84. 



