On Cretaceous Cephalopoda from Zululand. 237 



umbilicated Schloenbachia (Prionocyclus) forms that appear in the 

 Lower Senonian," aud to be closest to A. paon, Eedtenbacher, and 

 to A. haberfellneri, Hauer. The genus Barroisiceras, however, to 

 which these two species belong, is characterised by a simplifying 

 suture-line ; and whereas its typical branch develops a concave 

 periphery, another group (with acute periphery) tends towards certain 

 Tissotids. Solger ,* who doubtfully classed A umbulazi in M^mier^ceras, 

 appears to have been much nearer the mark. The young A. umbulazi 

 reproduces the ornament of Muniericeras lappareuti, Grossouvre.f and 

 has chevrons on the venter, but no keel (Fig. B2). But before this 

 stage, the young A. umbulazi reproduces Puzosia, with constrictions 

 (Fig. B 3), and the suture-line throughout shows great resemblance 

 to that of many Desmoceratids. There is, however, at least an 

 equally great similarity, shown by the apparently continuous series 

 Sonneratia-Cleoniceras and of Hoplites-Pleurohoplites +-8chloenbach la 

 with certain contemporary Desmoceratids ; also, possibly, Munieri- 

 ceras itself includes Prionotropid forms (Grossouvre's species, M. 

 yosauicum, Hauer sp., M. dresdense, Petraschek) and Desmoceratid 

 species, e.g. the lower Seuonian A. clypealin, Schliiter and Brauns,|| 

 and " Desmoceras " clypealoides, Leonhard,^" apparently connected 

 with the Turoniau Puzosia hernensis, Schliiter sp. Thus the presence 

 of constrictions on the inner whorls of P. umbulazi, and a suture-line 

 that resembles that of certain Desmoceratids, are not definite proof 

 that Pseudoschloenbachia be derived from Puzosia rather than from 

 Prionotropidae, via Muniericeras. Constrictions may appear in 

 Schloenbachia as well as in Pseudoschloenbachia and Gauthiericeras and 

 other genera (e. g. Hystatoceras, Anahoplites) apparently quite spon- 

 taneously, and one example of Schloenbachia varians in the writer's 

 collection shows constrictions, like Gauthiericeras four nieri, Grrossouvre 

 sp., with deep chevrons across the venter, accompanied by decline 

 of ornament and loss of keel.** At any rate, if comparison is at 

 all permissible with the rather distant Hatiericeras, a Desmoceratid 



* " Foss. Mungokreide," ' Beitr. z. Geol. v. Kamerun, II ' (1904), p. 205. 



f Loc. cit. (1894), p. 158, especially pi. xxxv, fig. 3. 



t Gen. nov. for studeri group, Jacob em. Spath (genotype, A. renauxiamis, 

 d'Orbigny, 'Pal. Frang. Ter. Crct./ pi. xxvii). 



Fcmcms-group only. 



|| de Grossouvre (loc. cit., p. 175) has pointed out that Brauns' form is 

 different from Schliiter's type. 



f "Fauna d. Kreidef. Oberschles.," ' Palseontogr.,' xliv (1897), p. 57, 

 pi. vi, figs. 2 a, b. 



** This excludes any possibility of a connection between Prohauericeras or 

 Pseudoschloenbachia and the true Schloenbachia. 



