568 ME. X. F. SPATH ON [Der. I913, 



48 per cent, of the diameter. It greatly resembles Neumayr's form 

 from the acanthicus zone, and also Protetragoniits quadrisulcatug 

 (d'Orb.) from the Tithonian. It is perfectly smooth, however, and 

 shows neither the sulci of the latter form nor the periodic ridges 

 indicated in Gemmellaro's figure of Lytuceras polycydnm. 



The whorls, although circular and hardly touching on the inner 

 part of the shell, seem to he greatly depressed at the end. It is 

 probable that this character is merely due to squashing of the last 

 whorl, which is incomplete. If not squashed, the specimen would 

 have greatly exceeded, in- this depression of the outer whoil, 

 L. liebigi (Opp.), which has been quoted from Jebel Za>_hu;iii together 

 with Argovian ammonites ; but, as it is a typical Tithonian form, 

 I am inclined to think the identification at fault. 



The specimen which A. de Riaz figures as L. cf. polyanchomemum 

 Gemm. is more involute than my form ; in all probability, its 

 section also is different. I have not come across the description 

 of any other widely-umbilicated Lytoceras from the transversarius 

 zone. 



Genus Ochetoceras Haug. 



OCHETOCERAS AR0LICUM (Oppel). 



1863. A. Oppel, ' Ueber Jur. Amm.' Pal. Mitt. Mus. d. K. Bayerisch. Staates, 



p. 188 & pi. li, figs. 1-2. 

 1907. L. Pervinquiere, ' Etudes de Paleontologie Tunisienne : I — Cephalopodes 



des Terrains Secondaires ' p. 18. 



The two specimens in my collection consist of only septate whorl- 

 fragments, but the characters of this thin and smooth tncariuate 

 form are very distinct, and the identification therefore reliable. 



The form is a characteristic fossil of the Argovian (Perviiquiere 

 says of the ' Lower Oxfordian '), and has been recorded already 

 from the Poste Optique on another side of the mountain of Zaghuan. 



Ochetoceras canaliculatum (Miinster). 



1830. Miinster, in C. H. von Zieten, ' Verstein. Wiirtt.' p. 37 & pi. xxviii, fig. 6. 



1831. L. von Bucli, ' Recueil de Planches de Petrif. Remarq.' pi. i, figs 6-8. 

 1863. A. Oppel, 'Ueber Jur. Amm.' Pal. Mitt. Mus. d. K. Bayeriscli. Staates, 



p. 157 & pi. li, fig. 3. 

 1898. A. de Riaz, ' Description des Ammonites des Couches a Peltoceras 

 transversarium de Trept (Isere) ' p. 49 & pi. xvii, figs. 4-6. 



My specimen agrees with the figures cited above, as also with 

 specimens that come from the transversarius zone of Aargau 

 and from Les Vraconnaz (Vaud). The form is a characteristic 

 Argovian ammonite, and occurs almost throughout the whole range 

 of the transversarius zone from South- Western Poland through the 

 Carpathians, the Alps, France, and Spain to North Africa. 



Ochetoceras sp. 



1875. Ammonites liispidus (Opp.) Favre, ' Description des Fossiles du Terrain 

 Jurassique de la Montague des Voirons ' M£m. Soc. Pal. Suisse, vol. ii, 

 p. 27 & pi. ii, fig. 8. 



This genus is further represented by the inner whorls of a form 



