234 Annals of the ftouth African Museum. 



example of M. sontoni (Baily), very close bo Baily 's type, with small 

 umbilicus, but comparatively smooth outer whorl (B.M. No. C19441, 

 after G-. C. Crick), also is given for comparison (Plate XX, fig. 4), 

 since it differs considerably from that figured by Woods and from the 

 original (faulty) drawing in Baily. 



Locality. Umkwelane Hill, Umfolozi. Coll. Dr. A. L. du Toit. 



6. MOETONICEEAS aff. UMKWELANENSE, CT. C. Crick. 



(Text-fig. D 2, p. 297.) 



1907. M. nmkwelanense, G-. C. Crick, Joe. cit. (Third Eeport), p. 228, 

 pi. xv, figs. 9, 9 o. 



Crick briefly characterised this species, which he considered to be 

 related to M. sovtoni and M. stangeri, as having a " subquadrate trans- 

 verse section, a little wider than high." The example to be described 

 (No. 5491) differs from the holotype (B.M. No. C18134) in several 

 respects, but in view of the great variability of the nearly related M. 

 soutoni, of which a large number is available, it is considered in- 

 advisable to separate the present example from the specimen figured 

 by Crick. The dimensions of the specimen in the present collection are : 

 Diameter . . . . 250 mm. 



Whorl height . . 82 



Whorl thickness . . . . 69 



At a diameter of 160 mm. the measurements for height and thick- 

 ness are 60 mm. and 62 mm. respectively ; at 90 mm. diameter they 

 are 33 mm. and 39 mm. Whereas, thus, the inner whorls are wider 

 than high, and at a diameter of 160 mm. the whorl-height almost 

 equals the thickness, as in the holotype, on the outer whorl the 

 proportions are reversed and the whorl is higher than wide. It may 

 be added that at 250 mm. diameter the specimen is still septate. 

 Owing to the presence of an additional, if slight, tubercle on the lateral 

 area of the specimen here described, the whorl-section is more rounded 

 than that of the holotype, a feature still further accentuated by the 

 removal, away from the umbilicus and higher up on the side, of the 

 umbilical tubercle. 



At a diameter of 90 mm. there are only fifteen coarse costae per 

 whorl, as in the holotype. The suture-line is of the same general type 

 as that of M. soutoni; the position of the umbilical tubercle, however, 

 in the latter, corresponds with the second lateral saddle, whereas in the 

 present example it coincides with the inner branch of the bifid first 

 lateral saddle (compare Text-fig. D 2 with fig. 4 of Plate XX). 



The presence of a fifth tubercle, smaller than the others, as it also is 



