162 



SHELLS AND SHELL-FISH. 



PART I. 



both the animals and the shells are more diversified. 

 Hence, while scarcely any thing has yet been done in 

 determining the genera and sub-genera of the Helicino',, 

 nearly all those of the Achat'uKB have been named and 

 defined. It is time, however, to quit these general 

 remarks, and proceed to the sub-divisions of the family. 

 (153.) We arrange the whole of this group under 

 the five following families, which may be thus de- 

 fined : — 1. the Heliciuip, or testaceous snails, having 

 perfect turbinated shells more or less depressed ; the 

 aperture entire, but without teeth. 2. The Achatinee, 

 or spiral snails, the spire of whose shells is elongated 

 and conic. 3. The LimnacinKB, or river-snails, having 

 only two depressed or flattened tentacula, and no oper- 

 culum. 4. the Limacinrp, or slugs, having either no 

 shell, or one much too small to contain the body. And 

 5. the Lucernince, or terrestrial volutes, where the shell 

 is orbicular, depressed, or flattened, and the aperture 

 furnished with distinct teeth.* That the foregoing 

 series is probably the natural one, may be inferred from 

 the following table of analogies : — 



Analogies of the HELiciDiE. 



Sub-families 



of 

 Helicidcs. 



Analogical Characters. 



Families 

 of tile 

 Phytophaga. 



Helicin.e. 

 achatin^e. 



LiMNAClNJL. 

 LlMACIN,E. 



LUCERNIN^. 



C Spire most generally with the > helicid.e. 

 i whorls depressed. J 



Spire mostly produced. Trochid^. 



Outer lip considerably dilated. Turbid.e. 



Animal mu(;ii larger than its 



Naticid.c 



shell, the sides of which, ( 

 where it exists, are enve-( 

 loped in its mantle. 

 Depressed, or the spire very ^ 

 small; aperture furnished vHahotid^. 

 L with plaits. J 



These analogies are, of course, only appl 

 types of each, and are intended to be so 



Families 



of the 



Zoophaga. 



TURBIXELLID^. 



MuRICIDyli. 

 StROMBID/E. 



CYPR.EID.E. 

 VOLUTin^. 



i cable to the 

 understood : 



* The injustice of the attempt made by M. de Feru>sac to substitute a 

 new and artilivial nomenclature of his own for X\\q Ihiicidie, antl so tu 

 cancel the previous generic names of Lamarck, Draparnau(i,and of all his 

 predecessors, is without jtarallcl in this or perhaps any deiiartment of zoo- 

 Jogy, and can only be e<iualled by the confusion it has caused. 



