84 POLYGYRATIA-PLEURODONTE. 



Helix multispirata Hombr. & Jacq. (Manual, iii, 127) and H. 

 microphis Crosse, have been referred to Polygyratia by authors. The 

 first is probably a Charopa. The other has been made the type of 

 a group Microphyura by Ancey (Bull. Soc. Mai. Fr. v, 375). It 

 belongs to the genus Diplomphalus in Rhytididse (Manual 1 i, p. 114). 



Species. 



P. macgregori Cox, iii, 127. New Ireland. 

 P. r affray i Tap.-Can., iii, 128. Western New Guinea. 



* # # 



The series of genera next to be considered comprises a majority 

 of the large, solid-shelled Helices of the tropics and southern hemi- 

 sphere, both in the Old World and America. All discussion of this 

 and other primary divisions of the Helices is reserved for tie intro- 

 ductory portion of this volume, but certain brief notes may be of 

 use in this place. These genera share certain peculiarities of the 

 generative system : the female branch is without dart sack or other acces- 

 sory organs ; the male side has the penis continued beyond its papilla- 

 bearing apex in a narrow tube called the "epiphallus" which terminates 

 in a flagellum and vas defer ens. In most forms the epiphallus is as 

 long or longer than the penis itself ; but in some (such as Thelido- 

 mus) it is so shortened as to be inconspicuous, or even absent. In 

 Cristigibba this process of shortening has resulted in the com- 

 'plete degeneration of both epiphallus and flagellum. In these and 

 similar cases we must not mistake the structure resulting from de- 

 generation for a primitive condition. Such an error would he like 

 holding Ancylus to be a primitive gastropod on account of its (at 

 present) non-spiral shell, or like grouping the limbless lizards, An- 

 guis or Amphisbcena with the snakes. 



In the American forms the penis retractor is inserted upon the 

 penis; in the Asiatic and Australian it is usually upon the epiphal- 

 lus. 



The jaw is generally stoutly ribbed, but often by degeneration of 

 the ribs, smooth ; and this modification is certainly in some cases 

 not a generic or even subgeneric character. 



Genus PLEURODONTE Fischer de Waldheim, 1808. 



=Pleurodonte -f- Lucerna-\-Dentellaria-\- Caracolus -J- Isomeria-{- 

 Labyrinthus -\- Polydontes -j- Thelidomus -f- Liochila -f Eurycratera, 

 etc., of authors. 



