520 



MOLLUSCA 



Pig. 801 — Genital organs of Polygyra 

 (from Walker). 1, genital pore; 2, 

 sperm duct ; 3, oviduct ; 4, albuminous 

 gland ; 5, hermaphroditic duct ; 6, 

 hermaphroditic gland; 7, retractor 

 muscle ; 8 spermatheca ; 9, penis. 



ent : an European species, introduced into New Orleans and other places : 

 imported into New York for food. 



H. hortensis (Miill.) (Fig. 802). Shell yellowish, usually striped 

 with several revolving dark bands; aperture without teeth; peristome 



white; umbilicus closed; height 12 

 mm. : an European species, introduced 

 into eastern New England. 



H. nemoralis L. Like the above, 

 with black peristome: an European 

 species found at Burlington, N. J., and 

 in Virginia in trees. 



H. califomiensis Lea. Shell vari- 

 able in shape and color, globose, thin, 

 and transparent, shining, pale yel- 

 lowish, with a narrow, browm, re- 

 volving band, paler at its edges; 

 height 15 mm.; diameter 19 mm.: 

 California. 



2. Polygyra Say. Shell helici- 

 form (Fig. 722) ; aperture usually 

 dentate, 1 tooth being parietal and 2 

 on the lip, but they may be absent; jaw with about a dozen promi- 

 nent ribs; dart sac, genital mucous glands, and flagellum absent (Fig. 

 801); foot without marginal grooves: a North American genus with 

 125 species, which are most often found in moist and more or less open 

 woodlands. 



Key to the species of Polygyra here described : 



fli Aperture tridentate. 



6i Aperture distinctly ear-shaped P. auriformis 



63 Aperture not ear-shaped. 



Ci Umbilicus open P. tridentata 



Cj Umbilicus closed. 



di Diameter exceeding 20 mm P. palliata 



<fj Diameter less than 15 mm P. inflecta 



a. Aperture unidentate. 

 6i Aperture broad and more or less circular. 



Ci Umbilicus open P. tiiyroides 



Cj ITmbilicus closed P. albolabris 



5, Aperture very narrow. 



c, Surface of shell hirsute P. IIIRSUTA 



C2 Surface smooth P. monodon 



C3 Aperture ed«'utate. 



fc, Shell without spiral lines P. albolabris 



b. Shell with spiral lines. 



c, T'mbilicus open P. profunda 



Cj Umbilicus closed P. multilineata 



