CHAP. VI. TYPES OP 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 of Partula*} we return 

 again to B. hamastomus. 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. 



BULIMUS. 



ACHATINA. 



Sectional Analogical Sub-genera Sub-genera 



Types or Specie, Walter, ' 



Htemastomus. 



Interrupts 

 Lara. 



CLAUSILIA. Lubricus. 



HELICINA. Lyonetianus. 



CTCLOSTOMA. Australis. 



("Shell ventricose;1 

 j spire short ; | 

 -^ aperture in the }> BULIMUS. 

 j typical species 

 [_ 



ACHATINA. 



always rosy. J 



r Shell more slen-} 



-J der; spire ele- V BULIMULUS. COCHLICOPA. 



C vated. 



J 



rSpirelengthenedfl 

 | basal volution j 



-I smaller or very }> LEPTOSPIRA. MACROSPIRA 

 I little larger 

 L than the next J 



Aperture distort-} 



LEUCOSTOMA ? 



(. the base. ) 



f Outer lip thick-T 

 ened more than ) 



lar ; aperture I 

 ear-shaped. j 



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

 sisting of few whorls ; aperture auriform ; outer lip reflected, broad ; inner 

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

 nual, p. 77. If the student turn to the figure of B. melanostomus Zool. 111. 

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

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



N 2 



