1889.] NATURAL SCIENCES OF PHILADELPHIA. 191 



NOMENCLATURE AND CHECK-LIST OF NORTH AMERICAN 



l 

 LAND SHELLS. 



BY H. A. PILSBRY. 



The following list includes all of the species of land Pulmonata 

 known to me to inhabit America north of the Mexican Boundary. 

 I have taken this occasion to examine nearly every species (except 

 the Suceinea) and also to somewhat critically review the generic and 

 subgeneric nomenclature with a view to attaining greater stability. 

 The departures made from the ordinary usage of American mala- 

 cologists have been only such as seemed to me to be absolutely 

 necessary. The principal innovations are the following: 



PRISTILOMA Ancey. 



Mr. Ancey proposed in 1887 the subgenus Pristina for Z. lansingi 



and Z. steamsi Bid., two tiny Oregon species resembling Gonulus in 

 the shell. Later, the writer changecl the name to Anceyia (Pristina 

 being preoccupied), and redefined the group, pointing out the true 

 generic characters (which Mr. Ancey had overlooked). This name 

 also having been used for an African genus, Mr. Ancey replaced it 

 by Pristiloma. The genus is quite distinct from other American 

 modifications of the Zonites stock ; and in the combination of aculeate 

 or thorn-shaped marginal teeth of the radula with a strongly ribbed 

 jaw, can only be compared with the New Zealand genus Phacussa of 

 Hutton. I can see no reason for uniting this group to either Zonites 

 or Microphysa. 



PATTJLA Held. 



This division of the Helices seems to have sufficient individuality 

 to stand as a genus. It is composed of a large number of sub- 

 divisions founded on minor modifications of the shell, which varies 

 from large and strongly ribbed to minute, thin, subtranslucent ; and 

 whilst usually broadly umbilicated, is often more compactly con- 

 voluted, with only a minute perforation. The lip is always acute 

 and thin. The jaw is either striate or ribbed. Like Helix, the 

 genus is world-wide in distribution. In many of the sections I have 

 grouped here, the species, or part of them, are viviparous. 



PTYCHOPATULA Pilsbry. 



This name is proposed for a section of the genus Patula including 

 Neotropical Helices with minute, conical, thin shells, a narrow urn- 



