359 



Bulinus comptus (Melvill and Ponsonby). 

 Plate 18, figure 6. 



A lot of snails from the Mooi River, Natal, collected by Dr. 

 F. G. Cawston, appear to represent this species. As pointed 

 out by Connolly (1912), it may be distinguished from B. tropicus 

 *by the curve of the outer lip, which may be called normal and 

 regular in tropicus, but in comptus is usually distinctly flattened 

 and almost incurved for a short way below the suture.' In 

 comptus the aperture is nearly semielliptical in outline. More- 

 over, a careful study of Krauss' description and figures of Physa 

 diaphana fails to disclose any real differences from B. comptus, 

 so that we are inclined to regard comptus as a synonym of B. 

 diaphanus (Krauss). 



Fig. ^ 



length 



Width 



Ap. Length 



Ap. Width 



14.5 



9.5 



10.0 



5.0 mm. 



16.5 



10.0 



10.0 



5.0 



13.0 



8.5 



8.5 



4.0 



12.5 



7.5 



8.0 



4.0 



11.5 



7.0 



7.5 



3.5 



Bulinus alluaudi (Dautzenberg). 



Plate 18, figure 8. 



Four snails collected by Dr. Glover M. Allen in Lake Nganga, 

 near Mt. Kenya, Kenya Colony, ^ fit the descriptions and figures 

 of B. alluaudi better than those of any other Central African 

 form. As our figures show, it is very close to B. corneus and B. 

 masakaensis. All three forms may possibly be mere variations or 

 races of one specific type. For the present we hesitate to offer 

 synonymies. We may call attention to the very long and broad 

 aperture of B. alluaudi, which, together with the short, obese 

 spire and the wide umbilicus, seems to characterize the species. 



Length 



Width 



Ap. Length 



Ap. Width 





12.0 



9.0 



8.5 



5.0 mm. 



Fig. 8 



9.0 



6.0 



6.5 



4.0 





16.0 



11.5 



11.5 



6.0 



Apex broken 



13.0 



8.0 



8.5 



4.5 





^ According to Dr. Allen, Lake Nganga is a small crater lake between Mt. 

 Kenya and Fort Hall. 



