Professor R. Burckhardt — On Hyperodapedon Gordoni. 491 



jugular lying in front of it, vvhicli in its turn is connected again 

 with the peculiarly shaped jugular. This latter bone borders the 

 anterior portion of the temporal fossa, and forms, as far at least as it 

 is exposed, the base of its posterior limits. Two strongly developed 

 longitudinal ridges stretched across it, of which the lateral one, 

 which is the shorter of the two, is projected towards the quadrato- 

 jugular by means of rough spines. Its normal situation on the 

 skull is preserved only on the left side, from which it has been, 

 figured. Leaning against it and to the front of it, is the maxillary, 

 which I found to deviate considerably from previous descriptions. 

 The maxillary is edentulous, and separated from the exclusively 

 dentigerous palate-bone by a distinct suture, which is not only the 

 case in this skull, but I have been enabled to verify it in another 

 separate fragmentary bone in excellent preservation. Only a narrow 

 branch of it separates the anterior margin of the palatine from the 

 prasmaxillaries, without any indication of a ridge on the inner nasal 

 foramen. Dorsad it interlocks by means of a small angle only with 

 the prcemaxillary and the lachrymal bone. 



Not more than three bones are discernible in the roof of the mouth. 



The vomers join each other along the median line, but both their 

 anterior as well as their posterior margins are covered in this case 

 by matrix. On the right side they are in their natural relationship- 

 to the palatal bone, the maxillary, and the prcemaxillary. Not so on 

 the left, where the original contact has been disturbed by crushing 

 in such a manner that Huxley was tempted to suggest the existence 

 of inner nares in this particular place. For my own part I find 

 it most difficult to adopt this view, as I opine that they are more 

 likely to be found in the gap between the posterior margin of the 

 palate-bones, if the lower jaw could be separated from the rest of 

 the skull. 



The palatine bones themselves are curved, thinnish plates, with, 

 their anterior margins rounded off. Their posterior margins articulate 

 with the subcircular pterygoids, of which only the right one is com- 

 pletely preserved. 



The mandibular ramus is composed of several separate bones 

 similar to many other reptiles. They do not articulate on their 

 margins by means of jointed sutures, but overlap each other like 

 flakes, and therefore I'ender a clear and precise description somewhat 

 difficult. No doubt can prevail about the mandibulars. Their 

 curved sulci, placed at a short distance from the apices, appear to me 

 to be a good indication of the limits to which the horny sheaths 

 come in close contact with the bone, which, however, is not so far as- 

 might have been assumed at fix'st sight. Their posterior margin is 

 very indistinct, through injury to the outer crust of the bone, and 

 can therefore only be guessed. The mandibulary at this place is in 

 contact with two bones, one of which I take to be the articular,. 

 from the fact that it articulates with the quadrate bone, whilst the 

 other, the supra-angular, though represented only by its impression^ 

 nevertheless agrees with Owen's statement in regard to the corre- 

 sponding bone in Rhynchosaurus. The ventral margin of thfr 



