150 HELICIDiE. 



clature. The genera into whicli this family may be 

 divided^ as regards the British species, are as follows : — 



* Shell oval, usually not quite covered by the body. 1. Suc- 



CIKEA. 



** Shell globular or round, glassy, sometimes covered in 

 part by a lobe or expansion of the mantle. 2. Vitrina. 



3. ZONITES. 



*** Shell shaped like the last, but not glassy, nor any part of 

 it covered by the mantle. 4. Helix. 



**** Shell cylindrical: mouth often furnished inside with 

 teeth, and in one genus also with a moveable plate. 5. Bu- 

 LiMTJs. 6. Pupa. 7. Vertigo. 8. Balia. 9. Clausilia. 



***** Shell shaped like the last : mouth more or less notched 

 at the base, and sometimes also toothed. 10. Cochlicopa. 



11. ACHATINA. 



Genus I. SUCCrNEA *, Drapamaud. 

 PI. VI. f. 1-3. 



Body gelatinous, usually incapable of being quite contained 

 mthin the shell : tentacles 4 ; upper pair conic, lower pair very 

 short : foot large, oblong. 



Shell oval or oblong, thin, amber-colour : spire short : 

 mouth large. 



The Amber Snails are allied to the Limnace in form 

 and habits, as well as in some respects to the Slugs and 

 the true Snails, or Helices — showing that the order of 

 Nature is not like the steps of a ladder, but bears a 

 greater resemblance to chain- or net-work, every link or 

 mesh of which is connected with the other. These snails 

 are in a great measure amphibious. Mr. Benson men- 

 tions his having found our common species [S. putris) 

 creeping on stones under water in an Irish lough, in 

 company with species of Planorbis, Bythinittj and Physa, 



* Amber-colovir. 



