Vol. 69.] JURASSIC AMMONITES FROM.JEBEL ZAGHUAN. 541 



a few interesting facts, despite the circumstance that the small 

 collection consists of casts and impressions which are not in a very 

 good state of preservation. In consequence, specific determination 

 has proved tedious, and, so far as some worn Upper Jurassic 

 specimens are concerned, too unsatisfactory to warrant the ex- 

 pression of an emphatic opinion. But the observations modify 

 the current opinion, insomuch as there is now good evidence in 

 favour of the presence of the zone of ReinecJceia anceps, hitherto 

 believed to be absent, with all the other strata intervening between 

 the Middle Lias and the Corallian. Domerian (that is, Middle 

 Liassic) ammonites are also recorded for the first time, and the 

 discovery of a rich cephalopod fauna of Argovian age throws inter- 

 esting light on certain ammonites described by previous authors 

 as of Lower Tithonian age. 



It is a matter for regret that further stratigraphical observations 

 or visits to the locality were impossible. 



II. The Jurassic Bocks op Jebee Zaghuan and their 

 Cephalopod Fauna. 



(1) The Lias. 



The Lias is represented at Zaghuan by thick, massive, bluish- 

 grey limestones of confused stratification. The base is unknown, 

 and it is impossible to say at present which are the oldest beds 

 represented. The late Prof. Baltzer 1 had collected a number of 

 Liassic ammonites in 1893, and the list compiled with the help 

 of Prof. Mayer-Eymar, and published in 1895,- included (besides 

 belemnites and lamellibranchs) forms of the following Lower 

 Liassic genera : Vermiceras [Arietites], Coroniceras [Arietites], 

 Arnioceras [Arietites'}, Arietites, Derocevas \2Egoceras\ Anclro- 

 gynoceras [xEgoceras], Platypleuroceras [JEgoceras] ; and also the 

 Toarcian Dactylioceras [Coeloceras] anguinum (Bein.). 



They are the only Liassic ammonites that have ever been 

 recorded from Zaghuan (and, indeed, from the whole of Tunisia), 

 and were collected below the ridge near the Col de Bourzen, 

 partly among the screes. The matrix is not the same in all the 

 specimens, and the curious mixture of Lower, Middle (to French 

 geologists), and Upper Liassic forms seems to have made both 

 Dr. Pervinquiere and Prof. Haug somewhat sceptical about the 

 identifications. The former 3 records only little-determiuable 

 belemnites and Terebratulce from these limestones ; but M. Ficheur 

 and Prof. Haug 4 found, besides belemnites 'of the acuti group,' 

 ' Pygope ' aspasia Meneghini (Yon Buch), a brachiopod common to 



1 ' Beitrage zur Kenntniss des Tunisischen Atlas ' N. Jahrb. vol. ii (1893) 

 pp. 26-41. 



2 Id. ibid. vol. i (1895) pp. 105-106. 



3 ' Etude Geologique de la Tunisie Centrale' 1903, p. 29. 

 i C. R. Acad. Sci. Paris, vol. cxxii (1896) p. 1354. 



