Mr. D. M. S. Watson on the Cynodontia. 519 



interlocked, the pre- and septomaxillarics are missing and the 

 anterior ends of both dentaries have been broken away — 

 removed, strangely enough, so as to leave two premolar teeth 

 completely exposed to the base of the root, these teeth 

 remaining in their natural position. There can be no doubt 

 whatever that this loss is due to the bite of another animal on 

 the fresh head with the muscles and gums intact. 



In general morphology the skull is identical with that of 

 Goinp/iognathiis } differing from G. browni (Ann. & Mag. Nat. 

 Hist. ser. 8, vol. viii. p. 2i»3 &c.) in the shorter snout, longer 

 temporal fossae, and wider occiput. Minor differences of 

 interest are the smaller area of the frontals and lachrimals. 



The upper dental formula is i. ?, c. 1, pm.? 2, m. 8. 



The interest and generic distinction of the specimen lies in 

 the brain-case and quadrate region. 



The quadrate complex consists of a small quadrate lying- 

 in a depression on the front face of the lower edge of the 

 squamosal, and attached to that bone by the reception of its 

 caudally produced outer edga in a slit. This quadrate is 

 devoid of any trace of a pterygoid wing. To the outer edge 

 of the articular margin of the quadrate is fused the quadrato- 

 jngal — a very small bone whose lower edge is condylar, — the 

 upper part of the bone running up in contact with the front 

 face of the squamosal and being separated from the quadrate 

 by a foramen. It expands into a narrow sheath which spreads 

 inward between the quadrate and squamosal to be received in 

 a slit in the latter bone. Comparison of the whole arrange- 

 ment with the Gorgonopsids and Dicynodonts justifies the 

 separation of the two elements, although no suture is visible 

 between them. 



The biain-case, as shown from behind and from the side, 

 agrees with Gomphognathus in general morphology, but 

 differs in the much greater relative size of the foramen between 

 the prootic and the epipterygoid, which extends up to the 

 parietal and is obscurely divided into two by a process from 

 the front edge of the prootic. There is thus apparently a 

 suppression of the processus prooticus superior of Gompho- 

 gnathus. 



The epi pterygoid has a wide expansion Oil the side of the 

 brain-case and extends back to the usual process on the front 

 face of the prootic. It there terminates on both sides of the 

 specimen in a slightly thickened and irregular margin, being- 

 separated from the quadrate by a gap of more than 1 cm. 



The series of venous grooves which I described on the 

 biain-case of Gomphognathus appears in P rotacmon with great 



