216 Prof. R. Owen on the Occurrence 



Part II. Restoration of Cortpsodon. 



If I were restricted to a single specimen on which to deduce 

 the nature of an extinct animal, I should choose a vertebra to 

 work out a reptile, and a tooth in the case of a mammal. 



The characters, seven or eight in number, that may be 

 deduced from a reptilian vertebra have been pointed out in the 

 summary of the subsequent evidences which have contributed 

 towards the reconstruction of the Chondrosteosaurus. The 

 dental characters are fewer, yet still, as it has proved, suffi- 

 ciently significative of the genus founded thereon to guide 

 subsequent discoverers of fossils to a right reference of them. 



In the year 1844 a petrified fragment of lower jaw with one 

 entire tooth was dredged up from the sea-bed between St. Osyth 

 and Harwich, off the Essex coast. It came into the possession 

 of John Brown, Esq., F.G.S., by whom it was transmitted 

 to me for determination ; and it is now, with the rest of his 

 collections, according to his liberal bequest, in the British 

 Museum. The characters on which the genus of hoofed 

 quadruped was proposed, with the name Coryphodon^ are 

 detailed in the undercited work"^. From the mineral charac- 

 ters of the fossil I inferred that it had been originally imbedded 

 in an Eocene deposit of the Essex coast. 



This inference was supported by a second tooth, from a 

 different part of the jaw, which had been brought up in the 

 following year from a depth of 160 feet, out of the plastic 

 clay, in the operations of sinking a well in the neighbourhood 

 of Camberwell. It was submitted to me by Mr. Alport, author 

 of the ' Antiquities and Natural History of the Town of 

 Maidstone in Kent ' f. 



In the year 1876 Prof. O. C. Marsh, of Yale College, 

 Newhaven, United States, published an account of his dis- 

 covery, in a formation of the Rocky-Mountain region the 

 horizon of which he determined to be that of the " plastic 

 clay " or lower Eocene of England, of the following remains 

 of a large hoofed quadruped. 



The skull lacking the lower jaw, but with the maxillary 

 teeth so preserved as to determine the dental formula to be : — 



" Incisors |, canines |, premolars ^, molars |, x 2=44" J. 



The last molar and the canine proved the animal to 



♦ ' History of British Fossil Mammals and Birds,' 8vo, 1846, p. 299, 

 figs. 108, 104, 107. 



t Op. cit. p. 306, fig. 105. 



X The first notice of this interesting discovery appeared in 'The 

 American Journal of Science and Arts,' yoI. xi. May 1876; the more 

 detailed account from which I quote is given in vol. xiv. of the same 

 'Journal,' .July 1877, p. 81. 



