Mr. D. M. S. Watson on the Cynodontia. 507 



a conclusion placed, I hope, almost beyond doubt by the 

 description by myself (not yet published) of a series of forms 

 leading up to their structure. The other group appears to 

 have arisen independently from the Therocephalia. 



All the recent discussions of Cynodont affinities have been 

 founded on Gomphognathus (Diademodon), the structure of 

 whose skull is known in very great detail (Broom, 1912 ; 

 Watson, 1912 and 1913). Gomphognathus is, however, one 

 of the most advanced Cynodonts, and 3 hence less useful for 

 comparison with more primitive reptiles than an earlier form 

 would be. 



I therefore purpose to describe as fully as the material 

 allows other Cynodont forms in the ensuing paper. 



Galesaurus planicps, Owen, 1859. 



Type and only known material, a slightly crushed and 

 damaged skull from the " Rhenosterberg," Cape Province. 



The Rhenosterberg referred to forms part of the Sneewberg 

 Range, about 20 miles to the N.E. of Grraaf Reinet. Other 

 fossils from the same locality include LyUrosaurus and an 

 advanced Cynognathus-zone Cynodont, Gynochampsa laniaria. 



The matrix of the Galesaurus skull is that of the Lystro- 

 saurus skulls from the same locality, and it is hence not 

 improbably of Lystrosaurus-zone age — i. e., the base of the 



rn • 



lnas. 



The skull was well described by Owen (Q.J. G. S. vol. xvi. 

 }). 58, and ' Catalogue of Fossil Reptiles of IS. Africa/ p. 23, 

 pi. xviii.). 



The occipital condyle is double, the two presumably 

 exoccipital condyles being separated by a distinct wide gap. 

 The occiput is remarkably wide and low, very square cut. 

 It lias the usual Theriodont structure of an occipital plate 

 overlapped by a median interparietal and a pair of tabulars 

 which form the upper borders of the small post-temporal 

 fossae, which lie high up. The tabular does not extend down 

 to the paroccipital outside the fossa. The paroccipital process, 

 correctly determined by Owen, is very massive and distally 

 supports the squamosal. 



The parietals together roof the brain-case, forming an 

 unexpectedly wide intertemporal bar, and surrounding the 

 medium-sized pineal foramen. The posterior end of the 

 parietal unites with the interparietal and the tabular, and the 

 front face of its posterior wing is overlapped by the squamosal. 

 The anterior end of the paiietal is not terminated by a recog- 

 nizable suture, but it is obvious that it forms a short pointed 

 area on the top of the skull separated from its fellow nearly 



