On Cretaceous Cephalopoda from Zululand. 317 



intermediate ribs also may have a tubercle at this point, even when 

 single, giving the inner whorls a coronate appearance. After a 

 diameter of 10 mm., however, all tuberculation is lost, whereas 

 Krenkel's type shows the last tubercle only at a diameter of 15 mm. 

 This loss of tuberculation is a feature found in certain varieties of 

 "D."' tscheriiyschewi, Sinzow,* but much more typically shown in certain 

 Acanthoplites. A. bigoti (Seunes), Siuzow sp.,t e.g., has a very similar 

 outer whorl; and the suture-lines of this form, and of A. bigoureti, 

 Seunes sp., as figured by Jacob, J are not very different from that of the 

 present specimen. Seuues's type, however, and the form figured by 

 Perviuquiere,|| are less closely comparable. On the other hand, the 

 small example of Ch. seminodosum, the lateral and peripheral views of 

 which, as figured by Siuzow, greatly resemble the (somewhat less 

 depressed) South African form, instead of losing the original tubercle, 

 takes on a second one, that is to say, it becomes a more closely costate 

 type of Ch. cornnelianiim. 



The suture-line corresponds with that found in certain Acan- 

 thoplites, i.e. the biijoureti-bergerotii group, and with that of tlie 

 cornuelianum-meyendorffi group, referred to above ; ajso with that of 

 Ch. hambrovii, Forbes sp.^f Those of the typical Acanthoplites (aschil- 

 fdPH.xi* group)** and of the true Paralwplites (weZc/iiom-group)tt are 

 different. 



There is no close resemblance to any of the various forms of the 

 South American Aptian (e. g. A. roseamus, treffryanus, Karsten sp.+J). 

 of which there is a large series in the British Museum, and which 

 (with forms like d'Orbigny's A. crassicostatus, with A. peltoceroides, 



* Loc. oil., e.g. pi. iii, fi^. 4. 



f " Unters. einiger Annn. a. d. Unt. Gault Mangyschlaks und d. Kaukasiis," 

 ' Verb. Euss. Kais. Min. Ges.,' scr. 2, vol. xlv (1907), pi. iv, fig. 18. 



J Loc. cif. (Clansayes), p. 412, fig. 5; p. 415, fig. 7. 



Loc. cit. (1887), pi. xii, fig. 2, p. 568. 



|| Loc. cit. (1907), pi. vii, figs. 30 a, b. 



11" See fig. 3, pi. viii, taken at a diameter of 10 mm., from an Isle of Wight 

 specimen in the writer's collection. 



** In Sinzow, loc. cif. (1907), pi. v, e.g. figs. 1 and 3; also Anthula, loc. cit. 

 (1899), pi. x, fig. 3 b. 



ft In Sinzow, loc. cif. (1907), pi. ii, figs. 1-4; also Anthula, loc. cit. (1899), 

 pi. viii, fig. 4 c. 



II "Ub. d. Geogn. Verh. d. Westl. Columb., etc.," 'Amtl. Ber. 32. Vers. 

 Deutsch. Nat. F., etc.,' Vienna, 1858, e. <j. pi. ii, fig. 4 ; also Lea, " Notice of Ool. 

 Form. i. Am.," 'Trans. Am. Phil. Soc.,' Philad. (vii), N.S., 1840-1, pi. viii, 

 figs. 4, 5. 



Loc. cit. (1840), pi. lix, figs. 1-4. 



