VITRINA. 393 



Order GEOPHILA. 

 Eyes at the tips of elongated, cylindrical peduncles ; tentacles 

 retractile or contractile, cylindrical, shorter than and placed under 

 tlie 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 wliole length to the 

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

 the middk^ of the uj)per 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 baclv ; respiratory orifice sub-central, on the riglit side. Foot 

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

 orly. A^ent near the res})iratory 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. 



OeiiHS VITRI1\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 l)ase of tlie 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 with a median beak-like projection. Lingual mcml)rane 

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



