184 Annals of tJie South African Museum. 



A form with which it might seem possible to bring Bochianites 

 glaber into close comparison is B. oosteri Sarasin and Schondel- 

 mayer,* from the Swiss Neocomian. This is also devoid of 

 ornamentation so far as has been ascertained ; but it appears to be 

 well distinguished by the great breadth of the lateral saddle in 

 relation to the siphonal saddle, and by the deeply divided form of 

 the lateral saddle. This division is carried so far, indeed, that it 

 may be said that two lateral saddles are developed. If B. glaber 

 possessed in maturity a septal suture having the relations of lobes 

 and saddles similar to those exhibited in B. oosteri, it would be right 

 to expect that some signs of it would be evident even at an early 

 stage. Traces of the suture of B. glaber where the shell has attained 

 a diameter of 4 mm. are still of a very simple character, and show 

 no promise of such sub-division at a later stage of growth as that 

 which characterises the mature B. oosteri. Moreover, the septa of 

 B. glaber are much more closely approximated than those of the 

 Swiss shell, in which the length of the chambers is a special 

 feature. 



Bochianites undulatus von Koenen,f from the lower Aptian of 

 North Germany, is well distinguished from B. glaber by the well- 

 developed ornamentation and the deeply divided lateral saddle, as 

 well as by other features. 



Baculites rotundus Eeuss,| from the Planermergel of Bohemia, is 

 also a smooth, slowly tapering form, but without particulars of the 

 septal line it is impossible to make a close comparison. B. rotundus 

 may be a true baculite, and Pictet has even suggested that its real 

 position may be in the genus Hamites. 



GENUS HOLCOSTEPHANUS M. Neumayr (sensu stricto). 



The great majority of the ammonites included in the collections 

 under examination belong to that section of the original genus 

 Holcostephanus exemplified by d'Orbigny's Ammonites astierianus, 

 the form which was regarded by Neumayr to be the best known 

 typical species of his genus. To this species and some allied forms 

 Pavlow gave the name Astieria, when recognising that the wide 

 application of the name Holcostephanus was not in accordance with 



* Sarasin and Schondelmayer (1), part 2, p. 179, pi. xxiv., figs. 3, 4, and text- 

 figure 6. 



f von Koenen (2), p. 398, pi. liii., figs. 11, 13, 14. 

 J Eeuss (1), part i., p. 24, pi. vii., fig. 4 (1845). 

 Neumayr (1), p. 922. 



