CLASSIFICATION OF HELICES. XXX111 



Tail with a longitudinal groove above. Shell somewhat Zoni- 

 toid, unicolored, with sharp simple lip, neither thickened or 

 reflexed TELEOPHALLOGONA; 



IV. Genital system having an epiphallus and flagellum on penis 

 (but these structures obsolete in some Pleurodontes and Plani- 

 spiras) ; appendix or penis gland small if present ; female side 

 with no accessory appendages. Eggs small or moderate in size. 

 Jaw smooth or ribbed ; radula with two or more cusps on part 

 of the side teeth. Shell usually solid, the lip expanded or 

 reflexed EPIPHALLOGONA. 



V. Genital system having epiphallus and flagellum (rarely want- 

 ing) on penis ; a dart sack and mucus glands (rarely wanting) 

 on vagina, and frequently a diverticulum on the long sperma- 

 theca duct. Eggs of small size. Jaw ribbed, smooth or plaited ; 

 teeth with several cusps on marginals (except in Allognathus). 

 Shell solid or thin, often conspicuously banded BELOGONA. 

 Some few exceptions to the above scheme are due to degenerative 

 groups of the higher tribes, which simulate lower tribes, and are 

 only to be correctly placed by attention to the totality of their 

 characters. Of this sort are Cristigibba, which by degeneration of 

 penis and its appendages is like the Haplogona; and Ciliella, Meta- 

 frutidcola and Cochlieella, unquestionably Belogona, by the loss of 

 their dart apparatus resemble Epiphcdlogona. 



Tribe I, PROTOGONA. 



a. Jaw ribbed. North American forms. 



b. Penis retractor with trifid insertion ; a large ac, 

 cessory sack on penis; shell globose, unkeeled, white- 

 with translucent or brown bands, lip narrowly re- 

 flexed Pratieolella, p. 67. 

 bb. Penis retractor not split; no large sack on penis; 

 shell yellowish or brown. 



c. Lip well reflexed, often toothed, but no inter- 

 nal teeth ; striate above ; spermatheca duct 

 short Polygyra, p. 68. 



cc. Lip not in the least reflexed, but thickened 

 within ; texture glassy ; spermatheca duct 

 long Polygyrella, p. 78. 



aa. Jaw and soft anatomy unknown ; shell discoidal, with many 

 narrow whorls, 

 iii 



