1889.] NATURAL SCIENCES OF PHILADELPHIA. 193 



compelled to reject them entirely. The same objection applies to 

 many of the divisions made by H. and A. Adams. Albers, in 1850, 

 inaugurated what may be called the modern period in Heli- 

 cology ; and von Martens and Pfeiftei have successively (and gener- 

 ally successfully) elaborated the structure of Albers. 



LYSINOE H. ana A. Ad. 



Consists of Helices of Old World affinities, confined to Mexico and 

 the West Coast. The species are excessively variable and plastic, 

 and their inter-relations can be understood only by one acquainted 

 with the conditions under which they exist. This knowledge of their 

 environment I do not possess ; and in the specific distinctions I follow 

 mainly Binney, with, however, a different grouping, and a number 

 of other departures from his arrangement. I cannot admit that 

 " Aglet la" (as distinct from " Arionta ") has any claims to the 

 slightest systematic rank ; nor do Helminthoghjpta or Micrarionta, 

 or " Euparypha" have any characters worth the time it takes to 

 write them down. Several species of " Helminthoglypta" have 

 varieties which are not " helminth oglyptous;" Mlcrarlonta is united 

 to the other species by H. rufocincta and other species; and as to 

 '• Euparypha," its species (H. tryoni, eireoletta, etc.) are merely arid- 

 country forms of the kelletti and intereisa group of Lysinoe. The 

 true Euparypha is a European section closely allied to Xerophila, 

 Frutieicola, etc., and belonging to a different phylum of Helices. 



POLYGYRA Say. 



Equals, in part, Anchistoma Ads., Try on, Fischer and others. 

 Includes as sections, Polygyra, Mesodon, Triodopsis, etc. 



I have adopted Polygyra as the name for that group of American 

 Helices characterized by a horn-colored striate shell, with reflected 

 white peristome, usually toothed within; ribbed jaw; genitalia 

 simple, without dart-sack or appendages other than the essential 

 organs, penis without flagellum, duct of the spermatheca short. The 

 subgenus thus defined is very homogeneous. Numbers of species 

 would go equally as well in Mesodon as in Triodopsis or Stenotrema. 

 H. levettei Bid., is as nearly related to Polygyra helictomphala Pfr., as 

 to Triodopsis, etc., etc. Atopa, Plectopylis, and a number of other 

 sections referred to "Anchistoma" by Tryon, Fischer, and others, 

 should be Avidely sundered from this subgenus. There are several 

 striking and important anatomical differences. On account of the 

 heterogeneous composition of Anchistoma I have dropped that name 



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