CHAP. VI. TYPES OF THE SUB-GENUS BULIMUS. 179 



the name of Partula), where the margin of the aperture, 

 instead of being completely reflected, as in all the other 

 types, is only very much dilated or spread out. This 

 peculiar character brings us, of course, to the confines 

 of the sub-genus Bulimulus; and by such shells as the 

 Bulimus melanostomus of Brazil (which will completely 

 answer to the characters given oi Partula*) we return 

 again to B. hcBmastomus. By arranging these species 

 in a column, as sectional divisions, they will be found 

 to represent the primary types of the spiral land shells 

 in the following manner : — 



Analogies of the Sectional Types of the Sub-genus Bu- 

 limus. 



^'^"^^^ Sectional Analogical ^"^.f"^^^ Sub-genera 



A:^:!!^.. Types or Species. Characters. ^^. ^o^^^the^ 



f Shell ventricose;"! 

 I spire short ; | 

 Bulimus. Hiemastomus. '\ aperture in the }> Bulimus- Achatina. 



I typical species j 

 \^ always rosy. J 



r Shell more slen-^ 

 Achatina. Interruptus < der; spire ele- 5- Bulimulus. Cochlicopa. 

 Lam. L vated. 3 



fSpire length ened;"! 

 basal volution 

 Clausilia. Lubricus. ■{ smaller or very ^ Leptospira. Macrospira 

 little larger I 

 than the next. J 



Aperture distort 



Helicina. Lyonetianus. ■{ HmJ w^h"'^t }■ Goniostoma. Leucostoma ? 



Cyclostoma. ^Ms/ra^w. <, fold on the nil- ''^^'^'CULA. Achatinella 



lar ; aperture | 

 ear-shaped. J 



* " Partula. Conical, smooth, spire equal to aperture in length, con- 

 sisting ot few whorls ; aj>erture auriform ; outer lip reflected, broad ; inner 

 lip reflected, with a slight prominence on the columella."— Sowr^'s Ma- 

 nual, \). 11. If the studeiitturn to the figure of B. mclanosto»iiis Zool. 111. 

 1st Series, he will find this description perfectly applicable ; yet this latter 

 has been arranged as a Bulimus, and placed in a diflerent family. 



N 2 



