CONNOLLY : MOLLUSCA PROM NORTHERN TRANSVAAL. 71 



processes consisting of a deeply inset and hardly noticeable un- 

 pointed columellar fold ; a strong, moderately entering, concave 

 plait at the outer angle of the paries ; a rather small tooth, single 

 in the Type but occasionally found with a smaller, second denticle 

 above it, half-way up the outer lip, corresponding to a single, small 

 exterior cavity ; and a very small tubercle on the extreme left of 

 the base. 



Long. 9-8, lat. 5-0 ; apert. alt. 3-2, lat. 1-8 ; last whorl 4-5 mm. 



Hah. — Luvinibi, Sibasa (Junod) ; Pepiti Falls (Harries). 



Of five specimens from Luvimbi, two have a single tooth on the 

 outer lip, as described in the Type ; in two this tooth is bifid, there 

 being a smaller cusp just above the other ; while in the fifth, the 

 upper cusp is represented by a minute swelling, only visible under 

 a strong lens. The shells vary in size from about 10-1 X 5-2 to 

 9-8 X 5-0 mm. 



Through the kindness of W. Falcon and H. C. Burnup a further 

 series of the same species has been available for examination, 

 strengthening considerably its specific value. It was collected by 

 C. Harries at Pepiti Falls, also in the Sibasa district, and consists 

 of ten shells, in nine of which the tooth on the outer lip is single and 

 in the other bifid ; while all show a distinct basal tubercle. They 

 represent a rather larger race than the Type set, ranging from 

 10-9 X 6-25 up to 12-5 X 6-3 mm., but are absolutely conspecific. 



In order to efiect a thorough understanding of the new species, 

 it is necessary to discuss at some length the small group of rather 

 conspicuous shells to which it belongs, whose distribution appears to 

 be restricted to the Northern and Western Transvaal. I have been 

 most kindly assisted in my study of this group by Mr. H. C. Burnup, 

 whose opinion, in which I fully concur, adds greatly to the value of 

 the following conclusions. 



Four species have so far been difierentiated : crassilahris, Craven, 

 1880; distincta, M. & P., 1893; eximia, M. & P., 1898; and 

 euschemon, M. & P., 1909. 



I have already ^ had occasion to unite euschemon with crassilahris ; 

 it now becomes necessary to place eximia in the synonymy of 

 distincta. Both these names were applied to a species remarkable 

 for possessing a minute sinual denticle near the top of the outer 

 lip, opposite the parietal plait, a feature by which, if constant, it 

 may be readily recognized. Distincta was described as being 

 12 X 4^ mm. in size, with two other teeth on the outer lip and a small 

 one on the base ; eximia as a rather smaller form, 9x4 mm., with 

 either one or two teeth on the outer lip and no mention of any oil 

 the base. There is, however, a basal swelling, or tubercle, which in 

 some specimens of the smaller form becomes a distinct denticle, 

 while intermediates in size occur which completely bridge the gap 



1 Ann. South African Mus., xi (1912), p. 70. 



