XI. Researches on the structure, organisation and classification of the fossil reptilia.—Part IX., Section 1. On the therosuchia

Abstract

The extinct order of fossil Reptilia named Theriodontia by Sir R. Owen in 1876, already been extended so as to comprise animals which are not included by the inal definition. It was founded upon skulls and fragments of skulls from South can rocks, chiefly obtained from localities near Fort Beaufort, the Sneeuwberg, the Rhenosterberg. No other portion of the skeleton was known, except isolated humerus referred to the genus Cynodraco, which cannot be proved e part of the same animal as the skull fragment with which it was associated. This order of animals was defined (loc. cit., p. 15) in the following terms: 'Denti- of the carnivorous type; incisors defined by position, and divided from molars by large laniariform canine on each side in both upper and lower jaws, the lower canine ssing in front of the upper, as in Mammalia:” This character had not previously in recognized among the Reptilia as having ordinal importance in classification, being only known as a mammalian character found in many different orders, such as Primates, Carnivora, Insectivora, Cheiroptera, Marsupialia, and certain ungulates. The fact that the character is not sufficient to define an order of mammals, has led me to doubt whether it is sufficient to define the animal group which some writers have named Theriodontia. Sir R. Owen did not adhere closely to the definition, since Procolophon was included under it, and in that genus there is no indication of such differentiation of the teeth, which are uniform in size, and conical.