XXX11 CLASSIFICATION OF HELICES. 



aaa. No mucus gland at tail. 



b. Holarctic forms Pyramidula, p. 42^ 



bb. E. Indian, Australian and Oceanic forms En- 



dodonta, p. 20. 



3. Jaw solid and smooth ; penis with flagellum (?) and appendix ; 

 shell moderately large, solid and strong. Pararhytida p. 52. 



The genera of this group rest upon much slighter characters than 

 those of Helicidw. Flammulina, Phasis and Amphidoxa are sepa- 

 rated mainly upon their geographic distribution, and many prove 

 to constitute but one genus. Endodonta and Pyramidula are re- 

 tained distinct for the same reason. The genitalia of very few of 

 the southern hemisphere forms are known, and the jaws and teeth 

 are not especially characteristic. 



Key to genera of Helicidce. 



The author has purposely abstained from assigning subfamily 

 rank to the natural tribes of Helices defined below. If they be 

 considered subfamilies, they may bear the names 1 Polygyrinse ; 2 

 Acavinas ; 3 Sagdinse ; 4 Camseninse ; 5 Helicinse. 



I. Genitalia simple; vas deferens inserted directly on the well- 

 developed, long penis, which has no epiphallus or flagellum ; 

 no dart sack or mucus glands; no diverticulum on spermatheca 

 duct ; eggs small and numerous. Jaw solid, ribbed or smooth; 

 marginal teeth with more than one cusp. Shell with lip thick- 

 ened within, expanded or reflexed, the embryonic whorls not 

 distinctly differentiated PROTOGONA. 



II. Genitalia simple, the vas deferens inserted directly on penis or 

 enlarged into an epiphallus ; no flagellum. No dart sack or 

 mucus glands, but sometimes having a blind sack or appendic- 

 ula high on vagina; eggs or young at birth very large, hard- 

 shelled. Jaw solid, smooth or vertically striate ; teeth all uni- 

 cuspid ; embryonic shell large, generally distinctly differentia- 

 ted from later growth by diverse sculpture or a terminal wrin- 

 kle. Shell large and solid MACROOGONA. 

 III. Genital system having an epiphallus and flagellum developed 

 on penis, and a complicated, flagellum-like appendix, or penis 

 gland; female side without dart sack or other accessory appen- 

 dages; eggs calcareous-shelled, or young born alive. Jaw 

 smooth or plaited ; rhachidian teeth tricuspid, laterals bicuspid. 



