VITRINA. 393 



Order GEOPHILA. 



Eyes at the tips of elongated, cylindrical peduncles ; tentacles 

 retractile or contractile, cylindrical, shorter than and placed under 

 the eye-peduncles, sometimes very small or wanting ; operculum 

 never present in the adult. Animal usually terrestrial. 



Family HELICID^E. 



Lingual membrane with numerous similar, transverse rows of 

 teeth. Jaws smooth, striated or ribbed, with or without a central 

 projection on its concave margin ; single, or composed of numerous 

 separate plates. Body elongate, attached its Avhole length to the 

 upper surface of the foot, or more or less spiral and prominent on 

 the middle of the upper surface of the foot. Eyes at the end of long, 

 cylindrical, retractile peduncles ; tentacles shorter, retractile, some- 

 times wanting. Mantle thin, small, discal or spiral, on the middle 

 of the back; respiratory orifice sub-central, on the right side. Foot 

 narrow, elongate, without a distinct locomotive disk, simple posteri- 

 orly. Vent near the respiratory orifice, central. Orifice of repro- 

 ductive organs usually below the respiratory orifice or behind the 

 right eye-peduncle. 



Shell very variable in form, sometimes rudimentary and internal. 



Ocnus VITKI1\A, Drap. 1801. 



Shell imperforate, pellucid, glassy, depressed ; spire short, whorls 

 two to three, rapidly increasing, the last dilated ; aperture ample, 

 peristome thin, often membraneous. 



Animal, body elongated, limaciform ; mantle covering the back 

 and neck, and extending to the base of the eye-peduncles, with one 

 or more processes or prolongations of its margin, which are re- 

 flected upon the shell ; tentacles very short. Respiratory orifice in 

 the mantle, behind its usual position in the Limaces. Generative 

 orifice behind and below the eye-peduncle. Jaw arcuate, concave 

 margin witli a median beak-like projection. Lingual membrane 

 with long slender teeth, centrals tricuspid, laterals bicuspid, in 



