340 PROF. OWEN OK THE SKULL OE MEGALOSAURUS. 



connexion with previous communications on the same subject, has 

 given rise. 



.Restoration of the Skull of Megalosaurus. ^ nat. size. 



15^ 



i | j ; i I i)M$r / ( 2$ / / 



32 32 



The restored portions are indicated by broken lines. 



Hermann v. Meyer, in his folio 'Zur Fauna der Yorwelt, Bepti- 

 lien aus dem lithographischen Schiefer ' (1859), affirms " the beak 

 (upper jaw and mandible) of the Pterodactyles to be formed, as in 

 birds, by a single bone, the intermaxillary ; " which bone he held to 

 be " prolonged backward to the region of the orbits " (ibid. p. 15) ; and 

 the sole modification which he admits, in the avian comparison, is 

 that of a greater density of the bone, in relation to its sustaining 

 and wielding teeth instead of being sheathed with horn (ibid.). 



Prof. Huxley sees, or surmises, the same structure in the portion 

 of the skull of the Megalosaurus described in the ' Quarterly Journal 

 of the Geological Society,' vol. xxv. p. 311 ; and, similarly, he founds 

 thereon an argument for the affinity of the great terrestrial Saurians 

 to the class of birds * ; but, as will be presently shown, there are other 

 and truer grounds for that affinity. 



From the evidence of the premaxillo-maxillary suture (PL XI. fig. 1, 

 s, s) in the present mature skull, it is improbable that such suture 

 should have been obliterated in the Oxford cranial specimen, the 

 mutilated condition of which might condone a conclusion supposed 

 to support a favourite hypothesis. The primitive separation of the 

 maxillary and premaxillary bones is retained throughout life in the 

 existing reptiles nearest akin to Megalosaurus. The conjecture, 

 therefore, that the jaw figured in plate xii. torn. cit. is simply the 

 premaxillary, " a possibility which must not be lost sight of, in view 

 of the resemblances between Dinosauria and Birds " (ib. p. 312), 

 has no support from fact, nor needs it. 



In his remarks, Prof. Huxley, with Hermann v. Meyer, holds that 

 the upper jaw in birds is formed by a premaxillary which is " pro- 

 longed backward to the region of the orbit." A portion of the 

 * Quart. Journ. Greol. Soc. vol. xxvi. 



