492 DR. R. BROOM ON THE STRUCTURE [Apr. 19, 



throw a considerable amount of additional light on the structui-e 

 of the jaw. 



One of the specimens includes a large part of both mandibles 

 and shows two sections of the jaws — one through the angle and 

 the other considerably further forward. These are shown in 

 figs. 9 & 10, Plate XXXV. In fig. 9 the section is through the 

 anterior part of the coronoid process. On the inner side of the 

 large dentary near the middle is seen the small surangular, with 

 below it two other bones which I believe to be the articular and 

 the angular respectively. In the more anterior section (fig. 10) 

 the surangular has almost disappeai'ed, and below it there are three 

 bones seen on section. The upper two are probably both articular — 

 the inner of the two almost certainly, while the lowermost element 

 ^s the angular. The detached portion of the dentary at the bottom 

 is due to a very short process at the angle. 



The other specimen is the almost perfect articular region of the 

 jaw. It is represented in PL XXXV. figs. 4, 5, & 6. The broad 

 articular is seen to be also faii'ly deep, and on passing backwards 

 it is seen to divide into an upper and a lower process. It is 

 supported on the outer side by the angular. Above the articiilar 

 is the dentary. Though in the specimen there is a slight gap 

 between the bones, it is probable that the dentaiy rested on the 

 articular. It will be seen that the dentary has a posterior process 

 which comes veiy near to the articulation. 



With regard to the mandible of Gomphognathus kannemayeri, 

 I am unable to accept as conclusive the first two of the text- 

 figures that accompany Seeley's paper (3). I am of the opinion 

 that in the first figure the drawing does not distinguish between 

 the delicate coronoid itself and plaster that has been added to 

 the specimen. In figiu-e 2 the drawing does not adequately 

 represent the back part of the actual specimen, on account of the 

 omission of the angular bone. The specimen is especially valuable 

 in that the jaws are open wide, and a view is thus obtained of the 

 antei'ior suii'ace of the quadrates. Fig. 2, Plate XXXV., represents 

 the appearance of the articular region, the posterior part of the jaw 

 being seen fromi above and the articular region of the skull from 

 the front. Fig. 3 is the corresponding region of the opposite side. 

 (When the specimen was first described by Seeley, the back part of 

 the left jaw was broken off and apparently believed to be lost. 

 Fortunately this portion is stiU preserved, and is now united with 

 the rest of the specimen.) In the lower jaw is seen the back part of 

 the dentary, consisting of the flat part which rests on the articular 

 and the thin coronoid process {cf. fig. 6). Beyond the dentary 

 and to the oiiter side is seen the articular end of the articular 

 bone. The whole structure of the articular region of the jaw is 

 very similar to that in Cynognathtts. The articular is, however, 

 developed more outwards, and the angular, which passes slightly 

 further back on it, is rather more strongly developed. 



On both the right side and the left the quadrate bone appears 



