240 Annals of the South African Museum. 



The hollow keel of Hauericeras, appearing comparatively late in 

 ontogeny, cannot be a development of the solid keel of Schloenbachia, 

 in which genus it appears after the costation, and, occasionally, tuber- 

 culation, and after the shell had become fairly involute. Similarly, 

 the ibex-like periphery of the young Pseiidoschloenbachia is not in favour 

 of a possible connection of this genus either with Schloenbachia or 

 with Prohauericeras. The various Natal forms indicate that this stock 

 had its own involute and smooth developments (P. griesbachi, Crick MS.) 

 and highly tuberculate and constricted forms (P. papillata, Crick MS.), 

 and transitions between these extremes. There are oxycone develop- 

 ments with simplifying suture-lines (Eulophoceras and Spheniscoceras), 

 and a hitherto unknown group (Diaziceras) that shows a superficial 

 resemblance to the South American Lenticeratids, and is interpreted 

 as a link connecting Pseudoschloenbachia with those genera (JEulopho- 

 ceras-Spheniscoceras) that carry the simplification of suture-line and 

 specialisation of whorl-shape to a higher degree. It is probable 

 that these clearly allied forms are only indirectly connected with 

 Desmoceratids, and that Pseudoschloenbachia via Muniericeras (and 

 like Gauthiericeras, to which probably 8. bertrandi, S.fournieri,Grros- 

 souvre,* and the forms of the Syrian Senouian have to be added) is 

 derived from Prionotropidae. 



8 and 9. PSEUDOSCHLOENBACHIA UMBULAZI, Baily sp. 

 (PI. XX, figs. 2 and 3 ; Text-fig. B 2-7). 



1906. Schloenbachia uinbulazi (Baily). Woods, " Cret. Fauna of 

 Poudolaud," Ann S. Afr. Mus., vol. iv, part vii, No. 12, p. 336. 

 (See there for synonymy.) 



Two specimens are referred to this form, the smaller one (No. 5494) 

 (PI. XX, fig. 2) agreeing particularly well in costation with Baily's 

 type-figure. Its dimensions are : 



Diameter . . .43 mm. 

 Height of last whorl . 51 per cent, of the diameter 

 Thickness .28 



Umbilicus ... 13 



The larger specimen (No. 5459) is less coarsely costate at the same 



* A specimen of " Schloenbachia " boreaui, Grossouvre, from the Middle 

 Coniacian of the Charente Inferieure (B.M. No. C7387) shows that the group 

 of " S." fournieri is more nearly allied to Gauthiericeras, and has nothing to do 

 with the probably Campanian Pseudoschloenbachia. 



