On Cretaceous Cephalopoda from Zululand. 235 



in examples of M. texanina (Romer), makes the Ammonite here dis- 

 cussed somewhat of a transition between the compressed form next 

 described and compared with M. soutoni, and Crick's holotype. The 

 inner whorls, however, are different in the two developments, and there 

 are other distinctions, as pointed out in the description below. In M. 

 soutoni, as well as in M. texanum (Romer) and M. quinquenodosum 

 (Redtenbacher), the umbilical tubercle is near the edge, and M. cam- 

 paniense, de Grossouvre, :1: though the young has a similar squarish 

 section and low keel, differs in its dichotomous costation. 



It may be added that in the holotype of M. umkwelanense the keel 

 has quite disappeared near the end a feature of great significance, but 

 not sufficiently apparent from the original figure. In the present 

 example the two outermost tubercles are not quite so close, the keel 

 between them not quite so feeble and not quite lost at the end. 



Locality. Umkwelane Hill. Coll. Dr. A. L. du Toit, 



7. MORTONICERAS sp. aff. souTONi, Baily sp. 



A large but somewhat fragmentary example (No. 5492), of 180mm. 

 diameter, agrees with the evolute specimen figured by Woods,t and 

 has fairly smooth inner whorls, with the lateral tuberculatiou only just 

 indicated. The ribs also are, then, quite indistinct. The five 

 tubercles become as conspicuous as they ai'e in Woods' example and in 

 Redtenbacher's M. quinquenodosum,* only just before the beginning of 

 the body-chamber (at a diameter of about 100 mm.). The body- 

 chamber, however, develops increasingly strong tubercles, which 

 character separates the example here described from the typical and 

 more involute M. soufnn! ,- for Baily's type shows decline of tuber- 

 culation at a stage when the present example develops its strong 

 tuberculation, and in the specimen of M. soutoni mentioned under M. 

 woodsi (see supra, p. 234) the outer whorl becomes almost smooth. 

 There are twenty-seven costae, as in the specimen figured by Woods ; 

 near the end of the specimen the whorl-height is 64 mm. as compared 

 with a thickness of 55 mm. The whorl-section, thus, is considerably 

 thicker than that of M. texanum, Romer, which, however, it greatly 

 resembles in the spacing of the tuberculation. 



The writer agrees with Woods || in considering M. bontanti, de 



* Loc. cii. (1894), pi. xiii, figs. 1 and 3. 

 t Loc. cit. (1906J, p. 337, pi. xliii, fig. 1 a. 



t " Cephal. Fauna d. Gosau-Sch. i. d. N.6. Alpen.," ' Abb. K.K.R.A.,' vol. v 

 (No. 5), 1873, p. 108, pi. xxiv, fig. 3. 



' Die Kreidebild. v. Texas, etc.,' Bonn, 1852, p. 31, pi. iii, fig. 1 Z> (and 1 ?). 

 || Loc. cit., p. 338. 



