150 HELIOID^E. 



clature. The genera into which this family may be 

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



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



SUCCINEA. 



** 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. 



BULIMUS. 6. PUPA. 7. VERTIGO. 8. BALIA. 9. CLAU 



SILIA. 

 ***** g ne ii shaped like the last : mouth more or less 



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



COCHLICOPA. 11. ACHATINA. 



Genus I. SUCCI'NEA*, Draparnaud. 

 PL VI. f. 1-3. 



2 'BODY gelatinous, usually incapable of being quite con- 

 tained within 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 Limncece 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, Byihima, and Physa 



* Amber-colour. 



