246 Annals of the South African Museum. 



There are twelve septa on the last whorl. .The most striking 

 characteristics of the suture-line are the very deep external lobe and 

 reduced first lateral lobe, the trifid external saddle and the peculiar 

 rounding' of the terminal folioles of all the saddles. These characters 

 are found in the suture-lines of Lenticeras audit, G-abb sp., L. baltai, 

 Lisson, and of Paralenticeras sieversi, Gerhard t sp.,* and of the two 

 close allies Eulophoceras and Splieniscoceras, which here are assumed 

 to represent developments of the same stock. On the other hand, the 

 suture line of " Barroisiceras " desmoulinsi, Grossouvre sp., as figured 

 by Solger,f though showing a superficial likeness, differs considerably 

 in its short external lobe, broad- stemmed external saddle and very 

 simple outlines, even of the internal portion. This species, however, 

 shows the greatest resemblance to the present species in its polygonal 

 whorl shape. There are differences in ornament, but the important 

 distinction is the presence of ventral tubercles in Grossouvre's form, 

 which, when worn, may present the appearance of an entire keel. 

 Solger's Cameroons specimens had an entire keel from the youngest 

 stage, but differ from the Zululand example in proportions, ornament, 

 and in having the peripheral tubercles elongated longitudinally. 

 One of Solger's specimens also becomes quite rounded ventrally in the 

 adult, so that these Couiaciau forms may belong to quite a different 

 stock from the presumably Campaniau Diaziceras. 



PseuJofchloenbarJiia papillata, G. C. Crick (MS.) sp., is a considerably 

 thinner form, with eight umbilical tubercles, each corresponding to 

 about four outer tubercles. It has a higher keel than is shown in 

 the sectional views of Gauthiericeras bertrandi and of G. fonrnieri in 

 Grossouvre, J and has much more prominent umbilical tubercles. But 

 in Pseudoschloeribachia the suture-line is quite complex and charac- 

 terised by a large and deep first lateral lobe. A comparison of 

 fig. B 4 a (p. 241) with fig. 1 A- of PI. XIX will show that whereas 

 Pseudoschloeribachia at 4 mm. diameter is much more advanced than 

 Diaziceras, as regards elaboration of the septal edge, the latter genus 

 shows a deeper ventral lobe, with the whole suture-line rising 

 towards the umbilicus generally a feature of later developments. 

 The Muniericeras stage of Pseudoschloeribachia cannot be traced in 

 Diaziceras, and it has already been pointed out that there is a 

 possibility of the keel of these two genera being a development of the 



* " Beitr. z. Kenntn. d. Kreideform. in Venezuela und Peru," in Steinmann, 

 " Geol. und Pal. v. S. Amer.," V, ' N. Jb. f. Min., etc.,' Beil-Bd. xi, 1897, p. 82, 

 text-fig. 6, and p. 79, text-fig. 5. 



t Loc. cit. (1904), pp. 168 and 169, text-figs. 53 and 54. 



| Loc. cit. (1894), pi. xxix, fig. (56, and pis. xxxv, figs. 1 b and 1 c. 



