Geological Society of London, 179 



Geological Society of London. — I. — February 2, 1876. — John 

 Evans, Esq., F.R.S., President, in the Chair. 



1. "Evidence of a Carnivorous Reptile {Gijnodru'kon major, Ow.) 

 about the size of a Lion, with remarks thereon." By Prof. Owen, 

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



The specimens described by the author consist of the fore-part of 

 the jaws and the left humerus of a reptile obtained from blocks of 

 Triassic (?) rock from South Africa, forwarded by the late Mr. A. G. 

 Bain, F.G.S. The upper jaw displays a pair of enormous canine 

 teeth, much resembling those of Machairodus, being of a very com- 

 pressed form, with the hinder trenchant margin minutely toothed. 

 There is no dentated border to the fore-part of the crown. No teeth 

 can be detected in the alveolar border of the right ramus of the lower 

 jaw, which extends about an inch behind the upper canine. In 

 the symphysial parts of the lower jaw the bases of eight incisors 

 and of two canines are visible, the latter rising immediately in 

 front of the upper ones, to which they are very inferior in size, and 

 being separated by a diastema from the in-cisors. In this character, 

 as in the number of incisors, the fossil resembles Didelphys ; and 

 in structure both canines and incisors resemble those of carnivorous 

 mammals. 



The left humerus is 10|- inches long, but is abraded at both 

 extremities. It presents characters in the ridges for muscular 

 attachment, in the provision for the rotation of the fore-arm, and in 

 the presence of a strong bony bridge for the protection of the main 

 artery and nerve of the fore-arm during the action of the muscles, 

 which resemble those occurring in carnivorous mammals, and espe- 

 cially in the Felidae, although these peculiarities are associated 

 with others having no mammalian resemblances. The author dis- 

 cusses these characters in detail, and indicates that there is in the 

 probably Triassic lacustrine deposits of South Africa a whole group 

 of genera (Galesaurus, Cynochampsa, Zycosaitrus, Tigrisuchus, Cyno- 

 suchus, Nythosaurus, Scaloposawus, ProcolopJion, Gorgonops, and 

 Cynodrahon), many of them represented by more than one species, 

 all carnivorous, and presenting more or less mammalian analogies, 

 for which he proposes to form a distinct order under the name of 

 Theriodontia, — having the dentition of carnivorous type ; the incisors 

 defined by position, and divided from the mulars by a large laniari- 

 form canine on each side of both jaws, the lower canine crossing 

 in front of the upper ; no ectopterygoids ; the humerus with an 

 entepicondylar foramen ; and the digital formula of the forefoot, 

 2, 3, 3, 5 ; three phalanges. 



The author further discussed in some detail the remarkable re- 

 semblances presented by these early Reptiles, in some parts of their 

 organization, to Mammals, and referred to the broad questions 

 opened out by their consideration. He inquired whether the 

 transference of structures from the Reptilian to the Mammalian 

 type has been a seeming one, due to accidental coincidence in species 



