248 Annals of the South African Museum. 



by being much thinner, by having more delicate ornamentation, a 

 narrower siphonal area, with less prominent and closer nodes, and 

 slight differences in the suture-line, e. y. the first adventitious lobe is 

 smaller than the second one in P. subkaffrarium, whereas the reverse 

 proportions are noticeable in the Indian species.* 



P. stantoni, var. bolli, Hyatt, f also is a close ally of the present 

 species, as is P. intermedium, Johnson, J the latter only distinguished 

 from the Zululaud form by a narrower ventral area and a wider 

 umbilicus. 



Locality. Umkwelaue Hill, Umfolozi, Zululand. Coll. J. S. Hedges. 



FAMILY: NOSTOCERATKLE. 

 GEN. NOSTOCERAS, Hyatt. 



12. NOSTOCEKAS ? NATALENSE, sp. 11OV. 



(PI. XXII, figs. 2 , 6.) 



A depressed turricoue (No. 2746) with the apical portion missing, 

 like the somewhat similar Didijmoceras ? newtoni, Whitfield sp., cannot 

 definitely be referred to either Didijmoceras or Nostoceras until more 

 complete specimens are known. The example is distinct enough, 

 however, to justify a new specific designation. 



The two and a quarter whorls preserved are septate throughout, 

 and though the suture-lines are too indistinct for delineation, they 

 appear to be of the same general plan as that of Nostoceras ? sul- 

 .angulatum, uov., with the external lobe and its small median (siphonal) 

 saddle between the two rows of tubercles. These are very prominent, 

 elongated, and continued on the under surface of the whorls into 

 simple and strongly forwardly inclined ribs, somewhat like those of 

 D. umbilicatum, Meek, but more oblique, and with a very steep 

 backward edge. On the upper surface of the whorls the costae 

 bifurcate at the tubercle, as in D. ? tricostatitm, Whitfield, || which 

 Hyatt^[ considered to be the possible geroutic stage of D. ? newtoni. 



* P. syrtale, Morton, var. tamulicum (Blanford), Kossniat in Boule, Lemoine 

 and Thevenin (loc. cit., II, 1907, p. 47, pi. xii, figs. 3 and 4), is very close to the 

 Zululand specimen, but apparently possesses the outer tubercle of P. syrtale. 



t Loc. cit., " Pseudoceratites," 1903, as above, also, e. g., pi. xliii, fig. 1. 



J ' The Geol. of the Cerrillos Hills, New Mexico,' part ii, ' Palaeont.,' School 

 of Mines Quarterly, vol. xxiv, no. 2, 1903, p. 206, pi. viii, figs. 27 a, b. 



" Invert. Cret. and Tert. Poss.," ' U.S. Geol. S. Territ.,' vol. ix (1876), 

 pi. xxii, fig. 5. 



|| "Pal. Black Hills, Dakota/" U.S. Geol. S.' (1880), pi. xv, fig. 7. 



H " Phylogeny of an Acquired Characteristic," ' Proc. Ani. Phil. Soc.,' 

 vol. xxxii (1894), p. 574. 



