1869.] HUXLEY HYPEKODAPEDON-. 143 



maxilla curves upwards, so as to leave a deep notch between itself 

 and the downwardly curved, beak-like anterior termination of the 

 snout, which appears to be formed altogether by the praemaxiUae. 

 Into this notch the surface of the matrix indicates that curved up- 

 ward processes of the mandibular rami fitted. Whether these pro- 

 cesses, and those of the praemaxiUae which projected between them 

 over the mandibular symphysis, ended in teeth, or not, cannot be 

 determined, as the extremities of the premaxillary processes are 

 broken away, and the mandibular processes are represented only by 

 impressions. But it is very likely that such was the case, if we may 

 judge by the analogy of some existing lizards (such as Uromastioo 

 spinipes), which present a very similar arrangement of the extremities 

 of the jaws. The two praemaxillae, however, are confluent in this 

 lizard, while they are distinct from one another in ITyperodaj^edon. 



Prom the dentary margin the outer surface of each maxilla in- 

 clines rapidly outwards, so that, even making allowance for partial 

 artificial depression, the measurement from the outer margin of one 

 orbit to the other is nearly double that between the dentary margins 

 of opposite sides. This conformation of the upper jaw also obtains, 

 though to a less extent, in Uromasticc. 



The orbit was large ; but its form cannot be accurately determined, 

 almost the whole of the roof of the skull being absent. There is a 

 cast of a strong supratemporal zygomatic arch, formed in part by 

 a prolongation backward of the jugal, and in part by a forward ex- 

 tension of the squamosal, as in Uromastioo. Clear indications of a 

 strong quadrate bone and of a pterygoid are also visible ; and the 

 remains of a long slender left cornu of the hyoidean apparatus lies 

 parallel with the left ramus of the mandible, on the ventral face of 

 the skull. No remains of any infratemporal zygomatic arch, such 

 as is found in Chelonia, Ci^ocodilia, and Aves, are visible ; but the 

 existence of such a structure is very probable from the analogy of 

 Ehynchosaurus. 



The remains of two broad plates of bone, not less than 3J inches 

 in length, with concavo-convex surfaces and a curved free edge, 

 which lie near the anterior end of block No. 1, most likely represent 

 the coracoids. A large impression of about the same length, which 

 must have been formed by a bone which was thin at both edges, 

 thin and expanded at one end, and thick, with an excavated terminal 

 surface, at the other, lies near one of the coracoids ; and I take it to 

 have been made by a scapula. What I suppose to be a cast of the 

 corresponding bone of the other side lies upon block No. 2; and there 

 are sundry scattered imperfect impressions of limb-bones, indicating 

 a fore leg of no great size. The right pubis and ischium have left 

 very distinct impressions of their dorsal surfaces at the hinder end of 

 block No. 1. In general form these bones resemble the correspond- 

 ing bones in existing lizards ; and the pubis has a great prepubic 

 process, as in the latter. But the pubis and ischium of the same 

 side seem to have united on the inner as well as on the outer side of 

 the obturator foramen, which appears to have been proportionally 

 much smaller than in existing Lacertilia. 



