200 PEOCEEDINGS OF THE GEOLOGICAL SOCIETT. [Jan. 25, 



of the structure of whose skull are known, and this only recently, 

 from the Rev, "W". Fox's unique specimen, first exhibited at the Meet- 

 ing of the British Association 1868, and described by Prof. Huxley 

 in the 26th vol. of our Journal. Of the skulls of Iguanodon Man- 

 telli and Megalosaurus BucMandi, the only parts which have been 

 determined are incomplete mandibles and fragments of maxillae. 

 The skull of Hylceosaurus is still, so far as I can learn, represented 

 by the single small fragment of the base imbedded, at the end of the 

 vertebral column, in the Tilgate-Forest slab, purchased by the British 

 Museum of the late Dr. Mantell, and figured by him in his * FossUs 

 of the British Museum,' and by Prof. Owen in the ' British Fossil 

 Eeptilia ; ' and the skulls of Polacanthus Foooii, Pelorosaurus, the 

 Cetiosauri, and Streptospondyli are altogether unknown. 



In August 1865 I saw in the Rev. W. Fox's collection a fossil 

 which he had recently found in Brixton Bay. It was plainly a 

 splendid fragment of what before its mutUation had been a very 

 large skull. A strong impression of its reptilian nature, together 

 with its marked dissimilarity to the skulls of the other orders of this 

 class found in the same formation (Chelonia, Crocodilia, and Ptero- 

 sauria), led me to assign Mr. Fox's skull to a Dinosaur; and its size 

 pointed to one of the largest, as Iguanodon Mantelli. 



In September 1869 I myself obtained at Brooke (a locality not 

 far from where Mr. Fox discovered his skull, and one famous for the 

 large number of Dinosaurian remains it has furnished) the hinder 

 part of a skull, which repeated the principal features of that which 

 I had seen in 1865 in Mr. Fox's collection, and which also supplied 

 several parts wanting in his, particularly the occipital condyle, 

 proving my impression of the reptilian nature of his skull to have 

 been well founded. 



Knowing Prof. Huxley to have been recently engaged on the 

 osteology of the Dinosauria, I showed him my prize soon after my 

 return to London ; and he confirmed my opinion of its probably 

 Dinosaurian nature. A paper upon it from him would have been 

 so valuable that it would have given me the greatest pleasure to 

 have left its description in his hands ; bnt his many and increasing 

 engagements have not allowed this ; and, unwilling to withhold any 

 longer from fellow- workers what, I believe, is a distinct addition to 

 the craniology of this interesting order, I now venture myself to 

 bring the skull under your notice. In doing this I am happy to 

 acknowledge my obligations to Prof. Huxley for assistance as valu- 

 able as it has been kindly rendered. 



The specimen consists of the nearly perfect cranium proper, the 

 facial segment having been broken oflP across the orbits. The freedom 

 of its outer surface from matrix, its polish, the smoothness of the 

 once rough fractured edges, and the presence of many recent Serpulce 

 upon it show that it had been during a long time lying exposed in 

 the sea before it was thrown upon the shore. 



Seen from above (PI. XI. fig. 3), its outHnes are roughly like those 

 of an hourglass, owing to the strong incurve of the temporal regions. 

 The deep temporal fossae are bounded in front by massive postorbital 



