580 JURASSIC AMMONITES EROM JEBEL ZAGHUAN. [Dec. I913, 



only by a wider and more rounded peripheral region, but probably 

 represent exactly the same horizon. 



EXPLANATION OF PLATES LII & LIII. 



Plate LII. 

 (All figures, except fig. 4, are of the natural size.) 



Fig. la. Protogrammoceras comacaldense (Tausch), var. zeugitunum nov. 

 Middle Lias (Domerian), Poste Optique, Jebel Zaghuan. 1 b. Orna- 

 ment of last whorl, where not weathered. (See p. 552.) 



2. Gen. nov. sp. nov. (aff. Lioceras ? grecoi Fueini). Middle Lias 



(Domerian), from the same locality. (See p. 556.) 



3. EeinecJceia aff. hungarica Till. Callovian, from the same locality. (See 



p. 558.) 



4. Perisphinctes cf. bieniaszi Teisseyre. Callovian, same locality. Part 



of suture enlarged. (See p. 560.) 

 5 a. Peltoceras toucasianum (d'Orb.). Argovian (zone of Pcltoceras trans- 

 versarium), near Sidi Bu Gubrin, Jebel Zaghuan. 5b. Outline-section 

 of the last whorl. (See p. 575.) 



Plate LIII. 

 (All figures, except fig. 2 c, are reduced to four-fifths linear.) 



Fig. 1. Phylloceras cf. subptychoicum Dacque. Argovian. Near Sidi Bu 



Gubrin, Jebel Zaghuan. (See p. 562.) 

 2 a. Sowerbyceras protortisculatum (Pompeekj). Argovian. Same locality. 



2b. Peripheral view, partly restored. 2c. Suture-line, magnified. 



(See p. 565.) 

 3a. Perisphinctes ( Grossouvria) cf. regalmicensis (Gemm.). Argovian. 



Same locality. 36. Peripheral view, partly restored. (See p. 570.) 

 4. Perisphinctes sp. nov., aff. trichoplocus Gemmellaro. Argovian. Same 



locality. (See p. 575.) 



Discussion. 



Mr. Buckman heartily congratulated the Society on the paper 

 which they had just heard. The Author showed rare ability in 

 his knowledge of ammonites, and was evidently working on what 

 the speaker considered to be the right lines. The Author had 

 shown that he possessed a full grasp of his subject ; and the 

 speaker could not help feeling pleased at the able use which the 

 Author made of a terminology for which he (the speaker) was so 

 largely responsible. The Author seemed to have a more intimate 

 acquaintance with the terms than the speaker had himself, and this 

 was an agreeable surprise. 



The Author, in reply, thanked the President and Fellows for 

 the kind and interested way in which they had received his paper, 

 and Mr. Buckman for his encouraging words. 



With regard to the fitness of the new generic terra Protogrammo- 

 ceras, the Author thought that if the HildoceratidaB were a mono- 

 phyletic family, the ancestral forms of the Toarcian genera would 

 have to be looked for in the Domerian predecessors and, therefore, 

 probably in the far too comprehensive genus Protogrammoceras. 

 Since not relationship but external resemblance to the later Gram- 

 moceras was chiefly referred to, however, when choosing Proto- 

 grammoceras, the Author agreed with Mr. Buckman in considering 

 that a non-descriptive term might preferably have been adopted. 



