XVI ANATOMY OP ACHATINID^E. 



aa. Peristome simple. 



b. Columella slightly truncated or obsoletely so; 

 apex rather nipple-like; shape long-ovate. W. 

 Africa. 



c. Axis imperforate. 



Pseudotrochus, xvi, p. 219. 

 cc. Axis rimate or perforate. 



Perideriopsis, xvi, p. 241. 



&&. Columella not in the least truncated, continu- 

 ous below. 



c. Oblong, with long spire, unicolored or with 

 Achatinoid striping. 



Limicolaria, xvi, p. 247. 



cc. Ovate, with moderate or short spire; 



streaked, but without oblique or zigzag 



stripes. Burtoa, xvi, p. 298. 



&&&. Columella abruptly truncated at the base; shell 



ovate or rarely oblong; apex of the trochoidal 



type. 



c. Shell varying from moderately strong to 

 very solid; middle tooth of the radula 

 narrow. Achatina, p. 1. 



cc. Shell very thin, very closely and deeply 

 striate, elaborately zigzag-striped; middle 

 tooth of radula wide. 



Callistoplepa, p. 125. 



Subfamily STENOGYRIN^. 



With the exception of Rumina decollata, little is known of 

 the soft anatomy of African members of this series of genera. 

 Ceras, Trichodina (Petriola) and Clavator are wholly un- 

 known anatomically. Of the other genera the jaw and radula 

 are more or less known. The jaw is much alike in all, and is 

 of the ordinary Achatinoid type. The radulae of all the 

 genera have the narrow central teeth of the Achatinidae, its 

 cusp simple or with minute side-points. In the laterals there 

 is more diversity: 



