894 DR. R. BROOM ON THE 



recognising that Gcdesaurus was in some way related to Dlcyno- 

 don, but hesitating to make a new Order on the evidence of a 

 single skull. As he still defined Anomodontia as reptiles with 

 " teeth wanting or limited to a single maxillary pair," it is mani- 

 fest he did not regard Gcdesaurus as really an Anomodont. 



In 1876, when Owen issued his ' Catalogue of the South African 

 Fossil Reptiles ' he put all the forms with a mammal-like dentition 

 into a new Order, the Theriodontia. In 1903 I showed that Owen's 

 Theriodontia is not a natural order, for it included two groups 

 which, though agreeing in having the dentition specialised into 

 incisors, canines, and molars, and possibly the one being ancestral 

 to the other, were yet so dissimilar that they could not be well 

 kept together. The more primitive group, which occurs only 

 in Permian beds, has simple molars, an open Rhynchocephaloid 

 palate, a tianspalatine bone, large angular and surangular bones, 

 a single occipital condyle, no acromion process, and apparently a 

 digital formula of 2, 3, 4, 5, 3. The higher group, which is known 

 only from Upper Triassic beds, has usually specialised molars, a 

 secondary palate as in Mammals, no transpalatine, small angular 

 and surangular bones, two occipital condyles, an acromion process, 

 and a digital formula 2, 3, 3, 3, 3. As Cynodontia was the name 

 fii"st applied to animals of the Gcdesaurus type, this title should 

 be retained for the higher group. For the lower forms I proposed 

 the name Therocephalia. The name Theriodontia shoidd be 

 dropped, as only likely to lead to confusion. 



Among the new forms described by Owen in his Catalogue is a 

 badly weathered small Cynodont skull somewhat resembling that 

 of Galesaurus and named Nythosaurus Icirvatus, In 1887 he 

 described another small but well-preserved skull which he believed 

 to be an additional specimen of Galesaurus. 



Most of our knowledge of the Cynodonts, however, is due to 

 Seeley, who, as the result of his expedition to South Africa, not 

 only came across the skulls of many new types, principally in the 

 collections of Dr. Kannemeyer, Mr. A. Brown, and the Albany 

 Museum, but for the first time obtained most of the skeleton of 

 some Cynodonts. In one paper issued in 1896 he described a 

 very fine skull with most of the vertebral column, the limb- 

 girdles, and portions of the limbs of a large carnivorous type, 

 which he called CynogncUhus a-(ctero7ioius, also a fine skull of an 

 allied form called Cynognathtis platyceps from the Albany Museum 

 collection. In other papers he described new types of Cynodont 

 reptiles with flat-topped molars. Of these the best known types 

 ai'e Gomphogiidtht(s, Diademodon, and Trirachodon. These were 

 regarded by Seeley as belonging to a distinct Order, which he 

 called Gomphodonim ; but as, apart from the specialisation of 

 the molars, there are no characters of any importance to distin- 

 guish the Gomphodonts from the Cynodonts, it seems to me 

 impossible to regard them as forming more than a Family of 

 the Cynodontia. 



Within the last eight years I have been so fortunate as to come 



