234 Reports and Proceedings — 



change in the order of nature occurred in the interval wliich elapsed 

 between the Cretaceous and Tertiary periods. Holding these views, 

 it is of course impossible for me to acquiesce in the principle accepted 

 by the author, because it appears to me to lead to the giving of two 

 names to one and the same thing. 

 ^ In discussing this question, I have carefully avoided any expres- 

 sion of opinion as to the nature of the differences between Pre- 

 Tertiary and later igneous rocks. I hope to deal with this question 

 independently on some future occasion. J. J. Harris Teall. 



laiBI^OI^TS J^ISTID ZPE-OOEIBIDIIsrG-S. 



Geo>l<3gical Society of London. 



L— March 19th, 18S4.— Professor T. G. Bonney, D.Sc, F.E.S., 

 President, in the Chair. — The following communications were read : 



1. " On Rhytidosteus capensis, Owen, a Labyrinthodont Amphibian 

 from the Trias of the Cape of Good Hope." By Sir Richard Owen,- 

 K.C.B., F.R.S., F.G.S. 



The author first noticed the discovery of certain forms of Amphibia 

 belonging to the genera Labyrinthodon^ Brachyops, Petrophryne, and 

 Bhinosaiirus, and called attention to certain typical peculiarities in 

 the structure of the teeth, the form of the bony palate and the double 

 occipital condyle. 



An imperfect cranium of the species now described as Bhytid- 

 osteus capensis was procured by Heer Swanepoel, from the Trias on 

 his farm at Beersheba, near Smithfield, in the Orange Free State, and 

 deposited by him in the Bloemfotitein Museum. 



This specimen, which was brought to England and submitted to 

 the author by Dr. Exton, consists of the anterior portion of the 

 skull with part of the mandible attached. The general form is 

 batrachoid, and one of the hinder palato-vomerine teeth, on being 

 examined microscoj>ically, exhibited the characteristic labyrinthodont 

 structure. 



The surface of the skull, and the characters of the premaxillary, 

 nasal, frontal, and prefrontal bones w^ere described. The jiarietals 

 and postfrontals are imperfect, the hinder part being lost. The 

 rami of the mandible are also imperfect behind, but a broken frag- 

 ment shows the articular surface. The vomerine bones were also 

 described, with the posterior nostril and the teeth before and behind 

 this oj)ening. The breadth of the bony palate at its hinder fractured 

 border is 5 inches ; the length of the part preserved 4^ inches ; the 

 mandible, when perfect, was probably from 11 inches to a foot in 

 length. The author also gave an account of the dentition wielded 

 by the premaxillary, maxillary, vomerine, palatine and mandibular 

 bones. 



The author pointed ont that the type of air-breathing vertebrates 

 to which the present genus belongs reached its highest development 

 in the Triassic period in Britain, Russia, North America, Hindostan, 

 and South Africa. The only known antecedent form from which 



