486 Professor R. Burckhardt — On Ryperodapedon Gordonu 



II, — On Htperodapedon Gordoni. 

 By Prof. Rudolf Btjrckhakdt, Ph.D., of the University of Basel, Switzerland. 



(PLATE XIX.) 



THE fossil to be discussed in the present memoir is the specimen 

 which formed part of the classical material used in the 

 discussion which was carried on amongst British geologists during 

 the second half of the present centurj'. So important a controversy 

 could hardly be restricted to the geographical limits of England 

 alone. 



In the question of the age of the Elgin Sandstones, considered 

 by Sir Eoderick Murchison to be Palaeozoic, it was Huxley who 

 pronounced upon it finally,^ after the discovery of and in his 

 subsequent description of Eyperodapedon.' His decision in this 

 geological controversy was given on the evidence derived from a far 

 less perfect specimen than the one represented on Plate XIX. It 

 also supplied Huxley with an opportunity for speculations concerning 

 the affinities of the animal with Sphenodon, from New Zealand, 

 a reptile which Dr. Giiuther had just then presented in all its 

 scientific aspects. On the other hand, these speculations carried 

 Huxley far out upon an ocean of geographical as well as of 

 geological hypotheses. 



A second specimen, which was obtained much later, afforded 

 Huxley a welcome opportunity to supplement his earlier description 

 of Hyperodapedon as regards its most prominent differences from 

 Sphenodon, the details of its skull and diverse other anatomical 

 points of no less importance. The motives which have impelled 

 me to undertake a re-examination of the subject may appear scarcely 

 obvious and require some explanation. 



During the perusal of the literature relating to the Ehynchocepha- 

 lians I was confronted very frequently by differences, essentially 

 anatomical in character, tending to a separation of the Ehyncho- 

 sauridse from the Sphenodontidas. In the first place I was unable 

 to assign any valid reason for a closer relationship existing between 

 them, whilst, on the other hand, the Ehynchosaurians appeared to 

 me to possess chai-acters important enough to justify the conclusion 

 of a complete connection between Chelonians and the remaining 

 Theromorphfe. Further investigation into the literature of the 

 subject and the material available disclosed so many enigmas, that 

 I at last decided to visit London and obtain permission to study the 

 original specimens in the Natural History Section of the British 

 Museum. 



According to Huxley's illustration of the skull I expected the 

 original object to be only a cast of the coarsest description, but in 

 this I was speedily undeceived after a personal inspection, and to 

 my great delight I perceived that I had one of the choicest of 

 originals before me which grace the grand collection of fossil reptiles 

 in the British Museum. 



^ Quart. Journ. Geol. Soc, 1859, vol. xv, p. 460. 



^ Op. cit., 1887, vol. sliii, pp. 675-693, pis. xxn-xxvii. 



