CHAP. VI. ANALOGIES OF THE ACHATINiE. 175 



families, before the whole tribe has undergone a careful 

 examination. 



(163.) The foregoing series, constituting the sec- 

 tional types of our sub-genus Achatina, will be ren- 

 dered more plain to the general reader, if thrown into 

 a table in the following manner : — 



Analogies of the Species in the Sub-genus Achatina. 



Sectional Sub-genera Genera 



Division of Analogical Characters. of of the 



the Species, Achatina. Achatinje. 



r Ovate; ventricose ; spireo 

 A. Zebra. < sliort ; outer lip simple, > Achatina. Achatina. 



t not sinuated. J 



r Ovale; aperture nearly orT 

 A. elongata. < quite entire; spire raore >Cochlicopa. Bulimus. 



C lengthened. 3 



A. perversa. [ ^^^[iJr.^^S.atoTlt^r"] ^--^^-^ ^--aiA. ' 

 A. Sultana. [ X^y?,Scl!ir "' ^ ^-]xe«co,.o.a; Hkucxna. 

 A.virginca. [ '^Eg^ned.'^""^^ '""""^ ' ^^ Achatinella. Cvclostoma. 



Now, this is the smallest group which can be made 

 out, next to the actual species which come under each 

 section ; and yet every conchologist who possesses an 

 extensive series of these shells, or even of those we have 

 named, must perceive that no other divisions, or sec- 

 tions, can be formed with any degree of propriety ; that 

 is to say, if he were asked to single out the most diver- 

 sified forms from the sub-genus Achatina, the above are 

 those he would probably fix upon. Now, this series, 

 small as it is, turns out to have a circular succession ; 

 and not only that, but likewise lo represent all the 

 sub-genera and genera of the family. Hence it would 

 seem that the essential character of this sub-genus is to 

 have the contour of the aperture simple — not sinuated 

 or dilated, as in the next sub-genus, Cochlicopa. The 

 Cochlicopa maculata thus seems to be neither an Achatina, 

 nor a distinct sub-genus, as some have imagined, for we 

 do not believe it is a marine moUusk. 



(l6"4.) The preceding analysis of Achatina inci- 



