542 mk. l. f. spath on [Dec. 1 9 13, 



the Alpine, Italian, and Sicilian Domerian. 1 Prof. Haug 2 therefore 

 classed the beds in the Middle Lias, and stated that the Toarcian 

 seemed to be absent in Tunisia. 



I have not been able to find Lower Liassic ammonites ; but my 

 search among the screes and rocks between the Col de Bourzen 

 and the summit-ridge was of a superficial nature, since I did not 

 recognize the locality at the time. I was fortunate enough, 

 however, to collect the following Domerian forms in loose debris 

 by the side of the path to the Poste Optique (975 metres) just 

 before that path reaches the final slope : that is, at a height of 

 about 900 metres : — 



Protogrammoceras comacaldensc Tausch, var. zeugitanum, nov. 



Pr. aff. costicillatum (Fucini), var. detr actum Fucini. 



Pr. sp. nov. 



[' Lioceras'] gen. et sp. nov. aff. grecoi (Fuc). 



Together with these specimens was found a fragment of an 

 ammonite similar as to matrix and mode of preservation, which 

 strikingly resembles the well-known Harpoceras bicarinatum Ziet. 

 non Miinster sp. ( = cumulatum Hyatt). On account, however, of its 

 association with Domerian fossils, I am inclined to think that my 

 specimen is a heterochronous homoeomorph of that Harpoceras. 

 rather than that the latter appeared earlier in Tunis than it did in 

 Europe, where it seems to be unknown in the lowest zones of the 

 Toarcian. In either case, the evidence in favour of the presence 

 of the Toarcian afforded by this fragment, which shows neither 

 umbilicus nor suture-line, is most unsatisfactory 3 ; and, further, 

 it is possible that the above-cited Dactylioceras anguinitm (Bein.), 

 collected by Prof. Baltzer, may really be one of the many similar 

 Domerian ' Ccelocerates ' recently described from Italian deposits. 

 Hence the Mesoliassic character of at least the main mass of the 

 grey limestones would remain established; whereas better evidence 

 would be required in confirmation of the presence of the Toarcian. 



1 The term Domerian is here used in Bonarelli's sense, that is, to denote 

 the Upper PJiensbachian (Upper ' Charmouthian ' in Bonarelli), which 

 corresponds with what the Officers of the Geological Survey call the Mi ddle 

 Lias: namely, the zones of Amaltheus margaritaius and of Palfopleuroceras 

 spinatum. Mr. Buckman (in 'Yorkshire Type-Ammonites') also uses the 

 term Domerian for this stage, but he restricts the term Charmouthian 

 to Bonarelli's Lower Charmouthian. Mr. W. D. Lang (in Geol. Mag. 

 dec. 5, vol. x, 1913, p. 401) introduces the term Carixian for the Lower 

 Pliensbachian (which latter has priority before Charmouthian, Liasian not 

 being acceptable) : that is, for the zones from Echioceras raricostatwm below, 

 up to, and including, that of JEqoccras capricornus. The new term deserves 

 general acceptance, since it enables us to keep the term Pliensbachian for 

 the whole, with its original connotation. The incoming of Seguenziceras and 

 other Hildocerates at the base of the Domerian (zone of Seguenziceras algovi- 

 anum of Buckman), together with the appearance of Amaltheids and the 

 almost complete extinction of the Liparoceratida;, is the most important 

 palaeontological characteristic. 



2 ' Traite de Geologie ' vol. ii (1908) pt. 2, p. 9S7. 



3 See also under specific descriptions. 



