Reports c& Proceedings — Geological Society of London. 333 



in them, producing a nuignetite-actinolite-staurolite I'ock, which 

 is of an entirely distinct type from that induced by the basic 

 intrusion associated with the Witwatersrand Beds, a micaceous 

 phyllitic rock. It is suggested that the Vredefort Granite, instead 

 of being ' Archsean ', is of a post-Pretoria - pre-Ivarroo age, if not 

 contemporaneous with, at least connected with, the same epoch of 

 igneous activitv as the ' Red Granite ' of the Northern Transvaal. 



May 27, 1914. — Dr. A. Smith Woodward, iMl.S., I'resident, in the 



Chair. 

 The following communications were read : — 



1. "On the Development of TraqophjUoceras luscomhi (Sow.)." 

 By Leonard Frank Spath, B.Sc, F.G!s. 



During his investigation of the Charmouth Lias Mr. W. D. Lang 

 has carefully collected abundant fossil material with reference to its 

 exact stratigraphical horizon, and the author is indebted to him for 

 permission to study the Ammonites. In the material, IVagophyllocenis 

 loscomhi (Sow.) is represented by hundreds of specimens (chiefly 

 young), and a study of the ontogeny of this interesting Ammonite 

 forms the basis of the paper. 



A considerable number of specimens were dissected back to the 

 initial chamber or protoconch, and their development was traced in 

 detail. Horizon and history (notably previous interpretations and 

 g&neric vicissitudes) are also discussed, tables of measurements are 

 given, and the other species of the genus [especially the pre-?'3?.r 

 Tragophylloceras vumismale (Quenst.), which had long been confused 

 with the ^Q'&t-ihex Tr. loscomhi (Sow.)] are reviewed. 



The evolution of the suture-line was worked out in great detail, 

 and one of the most important points brought out was the demon- 

 stration of a simple Fsiloceras-like suture-line persisting to a late and 

 post-constricted stage. The speculations regarding the bearing of all 

 the important facts upon the phylogeny of the genus Tragophylloceras, 

 and upon the connexion of the latter with allied lineages, will prove, 

 it is hoped, of general interest. The development of the suture-line 

 in Psiloccras and lihacophyllites is given for comparison. 



Since Tragophylloceras has morphic equivalents in Rhacophyllifes. 

 as well as in Analytoceras, but, hj its suture, is more nearly related 

 to EnphyUites and the Psiloceratidoe, it is argued that it can more 

 naturally be attached to those Moj.svarites descendants that Professor 

 Diener would group in the Pleuracanthitidee rather than to the 

 typical Phylloceratinae. 



The pre-Triassic ancestors of the ]\[onophyUitina3 are also reviewed, 

 and a new classification of the family Phylloceratiilaj is proposed. 



2. "The Sequence of Lavas at the North Head, Otago Harbour, 

 Dunedin (New Zealand)." By Professor Patrick Marshall, 31. A., 

 D.Sc, F.G.S. 



The North Head of Otago Harbour is situated 13 miles north-east 

 of Dunedin, and forms a more or less precipitou.s cliff ranging from 

 300 to 530 feet in height. This cliff presents a remarkably clear 



