194 PROCEEDINGS OF THE ACADEMY OF [1889. 



altogether, and have substituted Pohjgyra, the oldest name proposed 

 for a member of the subgenus as restricted here. The species are 

 nearly all American. 



PUPA. 



In this difficult genus I have had the advantage of the experience 

 of Dr. V. Sterki of New Philadelphia, Ohio, who has kindly 

 criticised my mss., pointing out to me the distinctions between V. 

 pentodon and V. curvidens; the identity of P. simplex with P. 

 edeutulu of Europe, and the generic position of this species, which 

 had heretofore been classed in Vertigo;* and also for information 

 regarding the curious little group Angudula, lately proposed by him. 

 The balance of the species I have left as in my original mss. I have 

 not been able to make certain other chansres recommended by Dr. 

 Sterki. P. sterri Voith, a European species, has been identified by 

 him from Colorado, but I am disposed to refer the form to some 

 variety of P. muscorum. 



SUCCINEA Drap. 



I have made no special study of this genus. The species are 

 a rranged alphabetically. 



VAGINULUS Blainv. 



The reasons for adopting the name Yaginulus instead of Veroni- 

 cella given by Fischer (Manual, p. 493, and Moll. Mex. et l'Amer. 

 Cent.) seem to me conclusive. 



Origin. In regard to origin of the snail fauna of the United 

 States, we may roughly divide the species into six categories, as 

 follows : 



(1.) Species introduced by human agency, such as Helix horten- 

 sis, Limax agrestis and maximus, Rumina decollata, etc. These are 

 principally European forms, and are as yet only locally distributed. 

 In the list they are indicated by having their numbers in brackets. 



(2.) Species inhabiting both Pakearctic and Nearctic regions. 

 Mostly minute boreal forms. Pupa muscorum, Helix pulchella, 

 Zonites radiatulus, Punctum pi/gmmim, etc., are examples. 



(3.) Pacific slope or Californian fauna. This fauna occupies the 

 region lying west of the Sierra Nevada, — a range which divides 

 America into two primary faunal provinces. This division was com- 

 menced with the upheaval of the Sierras in Jurassic times, constitut- 



* Dr. Sterki calls the subgenus containing P. edentula, "Edentulina" but 

 this name is preoccupied in Streptaxida: and elsewhere. 



