Yol. 69.] JURASSIC AMMONITES FROM JEBEL ZAGHTJAN. 545 



of the lower beds at that locality.' This does not apply now, 

 however. 



Peltoceras fouquei Kil. occurs in Algeria, together with trans- 

 versarium-zone ammonites ; but the type comes from Andalusian 

 beds of probably a higher horizon, and several authors record it 

 from the Lower Tithonian. The evidence afforded by this form, 

 therefore, is not satisfactory. 



Perisphinctes (Biplices) Icobelti Neum. is another ammonite 

 figured and described by Pervinquiere as a Lower Tithonian form. 

 Neumayr l stated that the horizon was not directly known ; 

 but he thought that, judging by the general appearance of the 

 ammonite, it undoubtedly belonged to the upper regions of the 

 Upper Jurassic. The matrix is a red limestone, identical with 

 the Diphya Kalk of the Southern Alps, and the type-specimen was 

 collected by Dr. Kobelt rather high up on the northern slope of 

 Jebel Zaghuan, at a spot where ammonites of fair size were 

 abundant. It is impossible to say whether this refers to some 

 locality on the Poste Optique, other than the greenish-grey lime- 

 stone outcrop mentioned by Pervinquiere — as at JBu Gubrin, 

 where similar red marble occurs, all the seventy specimens that 

 I collected were of small dimensions. Le Mesle, as we have seen 

 above, cited this form together with Peltoceras transversarium ; 

 a statement which caused Pervinquiere to point out that Le 

 Mesle, as well as Baltzer, had certainly mixed up ' Oxfordian ' 

 and Tithonian. The Tithonian age of this form, as well as of 

 Peltoceras fouquei Kil., seems by no means proved, however, and 

 Pervinquiere, who lays much stress on the resemblance of the red 

 marble matrix with his Lower Tithonian limestone from Jebel 

 Ben Saidan, ' known to belong without doubt to the beginning of 

 the Tithonian,' has himself been misled. It is well to remember 

 here that Pervinquiere includes Upper Kimmeridgian (that is, the 

 old ' acanthicus -zone ') forms in his Lower Tithonian. 



Perispliinctes simoceroides Font, is another ammonite, figured 

 and described by Pervinquiere as probably of Lower Tithonian age, 

 although the specimen came from the greenish-grey ' Oxfordian ' 

 limestone of the Poste Optique. It is possible, as that writer thinks, 

 that the form the type of which comes from the tenuilobatus beds 

 of Crussol appeared earlier in Tunis ; but the identification may 

 also be at fault, for Pervinquiere says : 



' at any rate, the ammonite can be more closely attached to simoceroides than 

 to the " Oxfordian" species sutneri Choff. or trichoplocus Gremrn.' 



The evidence afforded by those Phyllocerates and Lytocerates 

 which are of ' acanthicus ' age is equally unsatisfactory. The 

 specimens are imperfect casts, and it will be necessary to mention 

 in the specific descriptions that some of the identifications are 

 doubtful. The same may be said of Soiverbyceras loryi (Mun.- 

 Chalm.). That form — or, at least, two closely-allied, non-constricted 



1 ' Geogr. Verbr. d. Juraform.' Denkschr. K. Akad. Wissensch. Wien, vol 1 

 (1885) p. 139. 



