Vol. 69.] JURASSIC AMMONITES FROM JEBEL ZAGHUAN. 559 



short rib. This is the only notable point in which my specimen 

 differs from Reineckeia Jiungarica Till, and approaches R. cf . greppini 

 (Opp.) Till. I am inclined to consider it an intermediate form, with 

 the greppini stage persisting a little longer, and the branching 

 of the secondaries immediately off the umbilical border only 

 occurring once or twice near the end. 



R. transiens Till is a transitional form to still more perisphinctoid 

 ammonites, and also resembles my specimen somewhat closely. 

 It has fewer primaries, however (twenty-eight), and its .ura- 

 , bilious (37 per cent, of the diameter) is considerably smaller. 



The two ammonites which Waagen figures on pi. Ivii, fig. 4 & 

 pi. lix, fig. 1 (' Cephal. of Kutch ') as R. anceps (Rein.), although 

 they really belong to the greppini group, show a similar style of 

 ornament, but are more widely umbilicated (44 and 47 per cent.). 

 The first figure (= R. waageni Till) has less numerous and less 

 sharp costaB, and they divide more in the middle of the side, not 

 at the inner fourth. In it. eusculpta Till this point of bifurcation 

 has moved still more towards the middle of the side, whereas 

 the section is here quadrate. Waagen's second form ( = R. reissi 

 Steinmann) has the tubercles more strongly developed. 



The Reineckeia to which I referred in the first part of this paper 

 (p. 543), from Foum Islam en, Constant ine, differs from all the 

 forms mentioned here in its rounded whorls and strong costation. 

 It shows a highly coronate stage persisting almost to the end, and 

 belongs therefore to the true anceps group = substeinmanni group 

 of Dr. P. Lemoine. 



The suture-line is not shown on my specimen, but there can be 

 no doubt about the Callovian age of the ammonite. 



I may add that, as the Upper Jurassic was known to occur 

 on Jebel Zaghuan, I first endeavoured to compare my specimen 

 with those Kimmeridgian and Tithonian forms which were at one 

 time included in the genus Reineckeia. But the resemblance is, 

 in reality, only quite superficial. For example, Aidacosteplianvs 

 phorcus Font. 1 has similar dimensions, but distant tubercles, not 

 close primary costoe, around the umbilicus ; and in the genus Acan- 

 iliodiscus (as, for example, A. andreasi Ivil. 2 and A. cliaperi Pictet 3 ) 

 the tuberculate character of the ornament is still more distinct, 

 whereas the resemblance with certain forms of Himalayites Uhlig i 

 is also merely superficial. Apart from the costation, the character 

 of the constrictions and chiefly the inner whorls clearly distinguish 

 the Callovian Reineckeice from these Upper Jurassic forms. 



1 See E. Duniortier & F. Fontannes, ' Descr. des Amra. de la Zone a 

 Amm. ienuilohatus de Orussol' 1876, p. 108 & pi. xv, fig. 3 ; also P. de Loriol, 

 ' Monogr. Pal. des Couches de la Zone a Amm. tenuilobatiis de Baden 

 (Argovie) ' Mem. Soc. Pal. Suisse, vol. v (1875) pi. xvi, fig. 4. 



W. Kilian, 'Mission d'Andalonsie : II — Etudes Paleont. sur les Terrains 

 Secondares & Tertiaires de l'Andalousie ' Mem. Ac. Sci. Paris, vol. xxx (188D) 

 p. 670 & pi. xxxii, fig. 1. 



3 E. J. Pictet. ' Mel. Pal.' pt. 4, 1868, p. 242 & pi. xxxvii, figs. 1-3. 



4 V. Uhlig, 'Fauna of the Spiti Shales' Pal. Indica, ser. 15, vol. iv (1910) 

 pi. xxxviii. 



