PROFESSOR OWEN, ON THE RHYNCHOSAURUS. 359 



zygomatic arches, and terminating in a convex pulley for the articular 

 concavity of the lower jaw, — the large and complete orbits, and the 

 short, compressed, and bent-down maxilla?, — all combine to prove the 

 fossil to belong to the Lacertine division of the Saurian Order. 



The lateral compression and depth of the skull, the great vertical 

 extent of the superior maxillary bone, the small relative size of the 

 temporal spaces, the great depth of the lower jaw, prove that it does 

 not belong to a reptile of the Batrachian Order. The shortness of the 

 muzzle, and its compressed form, equally remove it from the Crocodilians. 

 No Chelonian has the tympanic pedicle so long, so narrow, or so freely 

 suspended to the posterior and lateral angles of the cranium. 



The general aspect of the skull differs, indeed, from that of existing 

 Lacertians, and singularly resembles that of the bird or turtle, and the 

 resemblance is increased by the apparent absence of teeth. The inter- 

 maxillary bones, moreover, are double, as in the Chelonia, and also 

 symmetrical, not united by a median ascending process ; but, with this 

 exception, all the more essential characters of the skull are those of 

 the Lizard. 



Of the proper parietes of the cerebral cavity, the portion formed 

 by the parietal and frontal bones is exposed. The parietal is traversed 

 by a thin, but high median crest longitudinally : the sides are convex, 

 and the breadth of the bone diminishes towards the occiput : here it 

 divides into two branches, which pass outwards, more transversely than 

 in existing Lizards. There is no perforation either in the parietal 

 bone, or in the coronal suture. This suture is transverse. At the an- 

 terior part of the parietal crest two lines diverge from each other at 

 a right angle to the upper part of the orbit, and separate the median 

 from the post-frontals ; a nearly transverse suture divides the fore-part 

 of the parietal from the post-frontals. The median frontal bone is single, 

 like that of the new-world Thorictes {Thorictes, Tejus) and Iguanas, not 

 divided, as in the Varanians. It expands slightly as it advances towards 

 the fore-part of the orbits, the oblique lines dividing the median frontal 

 from the post-frontals, and the supra-orbitary ridges are raised, so that 

 the interspace is slightly concave ; and the surface is also broken by 



BBS 



