HELIX. 



69 



HELIX, Link. 



Body elongated, semi-cylindrical, tapering to a point pos- 

 teriorly, convex above, plane beneath, the whole area forming a 

 locomotive disk ; integument reticulated by furrows ; mantle 

 simple, not extending beyond, and accurately fitting to the peri- 

 stome of the shell, into which the whole animal may retire ; head 

 obtuse ; eyes at the end of long, cylindrical, retractile peduncles ; 

 tentacles short, retractile ; generative orifice on the side of the 

 head, behind the right eye-peduncle ; respiratory orifice in the 

 collar, at the angle of the aperture of the shell, anal orifice im- 

 mediately adjoining. 



Shell discoidal, globose or 

 conoid, aperture transverse, ob- 

 lique, lunate or rounded, margins 

 distinct. 



Jaw arcuate, vertically ribbed, 

 margins crenulated. 



Lingual membrane broad, teeth numerous, centrals tricuspid, 



Fig. 114. 



Fig. 113. 



Jaw of Helix albolahris. [Mokse.] 



laterals bicuspid, uncini denticulated or serrated, centrals and 

 laterals sometimes simply conical with an acute tip. 



Subgenus MICROPHYSA, Albers. 



Shell umbilicated, depressed, thin, delicately striate, scarcely 

 shining ; spire flattened ; suture distinct ; whirls 4-5, rather con- 

 vex, gradually increasing, the last not descending ; aperture 

 roundly lunate ; peristome thin, perfectly simple, its extremities 

 converging. 



