246 INTRODUCTION. 



taining round, granular, nucleolated nuclei, and large, 

 round or elliptical, transparent cells, with nulcei similar 

 to those which lie free in the tissue. 



The integument of the tentaculoe is very freely sup- 

 plied with nerves from the supra-oesophageal ganglia. 



Taste. If existent, it is probably dependent upon 

 nerves distributed within the buccal body, and derived 

 from the stomato-gastric ganglia. The structure of the 

 lingual lamina precludes any idea of its existence there. 



Smell. The presence of this sense is undoubted, 

 though there is much discrepancy of opinion as to its 

 situation. I have suspected that it probably may be 

 placed in the blind sac, or depression, which opens just 

 below the mouth. This sac varies in its degree of devel- 

 opment in the different genera ; in Limax it is a super- 

 ficial depression ; in Vaginulus it extends backwards 

 beneath the buccal body for half an inch, is conical in 

 shape and yellowish-white in color ; in Bulimus fasciatus 

 it extends back, in the excavation of the foot, to the tail, 

 and is folded several times upon itself. 



Hearing. The acoustic apparatus consists of a pair 

 of transparent, vesicular bodies, placed upon the postero- 

 inferior part of the sub-cesophageal ganglia, one on each 

 side. They are placed in a depression of the ganglia, 

 formed by a separation of the nerve-tubuli as they pass 

 from and into the latter, immediately upon the gan- 



