298 Annals of the South African Museum. 



good agreement with Baily's type aud oue of Baily's co-types 

 (11368A),* are here given for comparison (PI. XXIII, fig. 3). The 

 distinct second lateral lobe and independent second lateral saddle (on 

 the umbilical wall) differ greatly from those of the specimen here 

 described, though the whorl-section, at a diameter of about 25 mm., is 

 that of a Peroniceras. At a stage corresponding to that of Peroni- 

 ceras sp. ind. (in Eedtenbacher : A. sp. iudet. cfr. A. tridorsatus, 

 Schl iiter f), the costae of M. stangeri continue across the ventral area 

 with its three faint keels, something after the style of the ventral area 

 in Pseudotropites uUraliasicus, Canavari in Wfiliner.J If Baily's 

 species is really of Upper Senonian age, as would appear from its 

 association with Hauericeras gardeni and Pseud opliyllites indra, it 

 forms a striking case of convergence of a late Mortoniceras, charac- 

 terised by its suture-line, towards the Lower Senonian Peroniceras. 



P. dravidicum occurs, in India, in the Middle Trichinopoly group, 

 which is considered to be of Coniacian (Lower Senonian) age. In 

 Europe, e.g. the North of France, || Peroniceras subtricarinatum, we&t- 

 phalicum and mmireti occur in the zone of Micraster cor-testudinarium. 

 Grossouvre^f has all the species of Peroniceras, the exact horizon of 

 which is known, in the Lower and Middle Coniacian. Boule, Lemoine 

 and Thcveuin* record what appears to be the Indian species from 

 Madagascar ; Solger describes it from the Cameroons. 



Locality. High ground on north side of United Mauuaii Creek and 

 Umsiuene River, almost opposite Junction. Coll. W. J. Wybergh. 

 The mode of preservation of this specimen (limonite, after pyrites ?) 

 is different from that of any other Zululand Ammonite that the writer 

 has examined. 



* Baily's type of A. stangcri in the British Museum (Geol. Soc. Coll., 

 No. 11366), a gigantic specimen of 325 mm. diameter, has the inner whorls 

 corroded ; the three co-types (11367, 11368 and 11368A) represent three slightly 

 differing varieties, but the large series in the British Museum includes many 

 transitions and shows the great variability of the species. 



f Loc. cit. (1873), p. 125, pi. xxx, fig. 3. 



J " Beitr. Kenntn. Tief. Zon. d. Unt. Lias N.O. Alp.," part vii, ' Beitr. Pal. 

 Ost.-TJng.,' vol. ix (1894), pi. iii, fig. 1 e only. 



According to Woods, loc. cit., pp. 346-7. Two examples of Pseudoschloenbachia 

 umbulazi, in the British Museum, from the Umtainvuna River, Pondoland, 

 have impressions of large Mortoniceras of stangeri affinity, in the same pieces 

 of matrix. 



(I Pruvost, " Les Animon. Senon. d. Nord.," ' Ann. Soc. Greol. Nord.,' vol. xxxix 

 (1910), pp. 365-8. 



<[ Loc. cit. (1894), p. 106. 



** Loc. cit. (1907), p. 42 (as " ScJiloenbachia (Peroniceras) subtricarinatum 

 d'Orb."). See also Pervinquiere, Zoo. cit. (1907), p. 250. 



