70 



HENRY CLIFDEN BUENUP. 



looked for in this species, and also the extent of the dis- 

 crepancy between the authors' original dimensions and those 

 indicated by their figure. To ascertain the dimensions repre- 

 sented by the figure, the height is taken from the artist's 

 dimension line, and the width is calculated therefrom, pro- 

 portionately to the height and width of the figure. 



Although my examples from Hennop's River tend towards 

 a more attenuate form than those from Amajuba, some of the 

 narrowest of the latter are, either actually or relatively, 

 narrower than the widest of the former ; so a larger series 

 than I have been able to examine Avould be necessary before 

 it could be seen if the narrower average would be main- 

 tained. Coincident with the more attenuate form, a deeper, 

 more oblique suture is observable ; but no increase in the 

 number of convolutions, beyond, perhaps, a quarter of a whorl, 

 can be traced ; therefore it would appear that the increase in 

 height is mainly attained by a looser coiling of the whorls. 



In the Hennop's River shells the aperture is less erect than 

 in those from Amajuba, sloping, in varying degree, from 

 right, above, to left, below; and the upper tooth of the 

 columellar lip is uniformly situate higher, being close up to 

 the junction of that lip Avith the Avail of the body-whorl. 



Melvill and Ponsonby draw attention to the alliance of this 



