520 



MOLLUSCA 



-.2, 



Fig. 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 (Mull.) (Fig. 802). Shell yellowish, usually striped 

 with several revolving dark bands; aperture without teeth; peristome 



white; umbilicus closed; height 12 

 inm. : 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. californiensis Lea. Shell vari- 

 able in shape and color, globose, thin, 

 and transparent, shining, pale yel- 

 lowish, with a narrow, brown, 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 : 



a t Aperture tridentate. 



6 X Aperture distinctly ear-shaped P. ATJBIFORMIS 



6 a Aperture not ear-shaped. 



G! Umbilicus open P. TEIDENTATA 



c a Umbilicus closed. 



d t Diameter exceeding 20 mm P. PALLIATA 



d t Diameter less than 15 mm P. INFLECTA 



a, Aperture unidentate. 

 &! Aperture broad and more or less circular. 



Cj Umbilicus open P. THYROIDES 



c, Umbilicus closed P. ALBOLABRIS 



6, Aperture very narrow. 



Ci Surface of shell hirsute P. HIRSUTA 



c a Surface smooth P. MONODON 



o a Aperture edentate. 



&! Shell without spiral lines P. ALBOLABRIS 



Z> a Shell with spiral lines. 



G! Umbilicus open P. PROFUNDA 



c a Umbilicus closed P. MULTILINEATA 



