SKULLS OF CYXODONT REPTILES. 



909 



The lacbrymal is of fair size. In Gom'pliognailius minor it 

 forms the front of the orbit and much of tlie inner wall. In 

 GompJiognathus poli/phagus it is considerably larger, extending to 

 part of the upper margin. 



Text-iijr. 175. 



Side view of the skull of Gompliognatlms minor. With the exception of the front 

 half of the snout and the lower jaw, the drawing is from tlie beautifully preserved 

 t\-pe in the JJritish Museum. The front of the snout is restored from a specimen 

 of Gomplwgnathus Tcannemeyeri in the British Museum, and the lower jaw is 

 from the lower jaw of the tj-pe of Cr. l-annemeyeri in the Albany Museum. 

 Both these latter are slightly modified to fit the skull of Gomplioffuatlnis 



The prefrontal forms most of the npper margin of the orbit. 

 In GompJiognathus polyphagus it is considerably smaller than in 

 G. minor, owing to its being encroached on by the larger nasal and 

 lachrymal. By uniting with the postorbital it completely shuts 

 out the frontal from the orbital margin. 



The frontal is relatively small, the two together forming 

 only about one-third of the interorbital space. As in all the 

 other Cynodonts except Bauria and Sesamodon, the frontals 

 posteriorly taper away to a point between the postorbitals. 



The postorbital is a fairly large bone with an external limb 

 which meets the jugal, forming the postorbital arch, and a posterior 

 process which lies along the parietal. In G. p>olypliagus the 

 postorbital bar is relatively slenderer than in G. minor. 



The jugal is very large. It is essentially similar- to that of 

 Trirachodon. The inferior process is much larger and the 

 posterior extension much deeper. It passes backwards some 

 distance behind the plane of the quadrate. 



The parietal is small and there is a small pineal foramen. 



The squamosal is extremely large. The inner portion 

 articulates with the parietal. The outer and anterior portion 

 lies above the jugal, forming with it a powerful zygomatic arch. 

 Inferiorly the squamosal supports the small quadrate. The 

 peculiar shape of the bone can best be understood from the figures. 



