1894.] Organisation, and Classification of Fo.ssil Reptilia. 291 



permit no doubt that they are true reptiles. The mammalian resem- 

 blances in the skull being paralleled in the other parts of the 

 skeleton, it may be affirmed that these fossils demonstrate a closer 

 affinity between reptiles and mammals than had previously been 

 evident. 



XVI. " Researches on the Structure, Organisation, and Classifi- 

 cation of the Fossil Reptilia. Part IX. Section 5. On 

 new Cynodontia." By H. G. SEELEY, F.R.S. Received 

 February 13, 1894. 



(Abstract.) 



The Cynodontia is a division of the Theriodontia in which there 

 are long and large temporal vacuities in the skull, formed chiefly by 

 the squamosal and malar bones ; in which there is no descending 

 pedicle to the squamosal bone ; in which the occipital condyle is 

 crescentic and imperfectly divided into two lateral parts; and in 

 which the hinder molar teeth, larger than the incisor teeth, develop 

 anterior and posterior cusps, are compressed from side to side, and 

 overlap, with shearlike action, the teeth of the mandible. The prin- 

 cipal new genera included in this group are Cynognathus, which is 

 known from several skulls, and one fairly complete skeleton ; and 

 the genus Tribolodon, which does not differ in a striking way from 

 the small Cynodonts previously known, referred to the genera 

 Galesaurus, Nythosaurus, and Thrinaxodon. 



The skeleton of Cynognathus crateronotus was found at Lady Frere, 

 near Queenstown. A single tooth of this genus had already been ob- 

 tained by Mr. Alfred Brown at Aliwal North. The skull is between 

 15 and 16 in. long, 8 in. high at the orbits, and higher at the occiput, 

 where it was about 9 in. wide. The lateral aspect is remarkably 

 Mammalian, owing to the great development of the dentary bone, 

 which forms a new type of lower jaw, and has a greatly developed 

 coronoid process, and the form of the zygoma. On the palate, the 

 palatine and transverse bones form a descending arch between the 

 rami of the mandible, as in Crocodiles, Sphenodon and Lizards. The 

 composite structure of the lower jaw is seen on its inner side. The 

 pre-frontal and post-frontal bones remain distinct. There is a small 

 quadrate bone embedded in the large squamosal bone. The latter 

 resembles that of Mammals, both in its extension along the zygoma, 

 and its expansion as a squamous plate on the side of the brain case. 



There are four incisors in each pre-maxillary ; their margins are 

 serrated. There appear to be but three mandibular incisors on each 

 side, so that the type resembles Cynochampsa, but there is no evidence 



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