260 ^ Transactions of the South African Philosophical Society. 



and palatine bones." Similar rounded teeth were found on the 

 mandible. Owen, in this first description of Endothiodon, does not 

 give a very clear idea of the anatomy of the new type. 



In 1879, Owen (5) published an important paper on the Endo- 

 thiodont Eeptilia, in which he gives further evidence of the structure 

 of Endothiodon bathystoma, and describes a well-preserved snout of 

 a new Endothiodont which he names Endothiodon uniseries. He 

 discusses at some length the affinities of the group, and concludes 

 that the Endothiodonts are allied to Oudenodon, but belong to a 

 distinct family of the order Anomodontia. The teeth of the upper 

 jaw he regards as belonging to the palatine bones. ,. 



In 1890 Lydekker (4) re-examined the British Museum Endothio- 

 dont specimens, and placed them in the family Endothiodontidae of 

 the sub-order Dicynodontia. Lydekker recognised that the upper 

 jaw teeth belong to the maxillary bone, and thus showed that 

 Endothiodon is even more closely allied to Oudenodon than had 

 been believed by Owen. An imperfect skull which Owen had 

 described under the name Theriognathus microps is believed by 

 Lydekker to be that of a young Endothiodon uniseries. I am not 

 aware that this opinion has been confirmed by any more recent 

 worker, and though any opinion of this nature expressed by 

 Lydekker must carry great weight, I am inclined to think that 

 Lydekker is mistaken. 



In 1892 Seeley (6) described and figured the lower jaw of 

 Endothiodon bathystoma, and showed the structure of the teeth. He 

 concludes that " all the characters of the dentition suggest near 

 affinity with the Theriodontia." 



In 1895 Seeley (2) further discussed the affinities of the Endothio- 

 donts. He pointed out for the first time that Pristerodon, of Huxley, 

 is really an Endothiodont. He also expressed the opinion that 

 Endothiodon uniseries of Owen should be made the type of a new 

 genus which he named Esoterodon. Owen in 1879 had suggested 

 the possibility of E. uniseries belonging to a different genus from 

 Endothiodon bathystoma, and though Lydekker agrees with Owen in 

 making the one genus include both species, I am of opinion that 

 Seeley's view is the more correct. Seeley described a new genus 

 Cryptocynodon allied to Esoterodon. This is founded on a small 

 imperfect skull which is too imperfectly preserved to reveal much 

 that is new in the structure of the Endothiodont skull. Seeley 

 differs from Owen and Lydekker in failing to recognise any marked 

 Dicynodont characters in the Endothiodont skull, which he con- 

 siders is much more nearly related to the Theriodont type. He 

 regards the Endothiodonts as forming a distinct sub-order Endothio- 



