HADROSATJRUS. 



83 



general character ascribed to the vertebrce of Iguanodon, those oi Hadrosaurus are 

 totally different. 



The convexo-concave vertebrae attributed to the cervical series of Iguanodon by 

 Drs. Mantell and Melville, are referred by Prof. Owen to a CrocodHe under the 

 name of StreptospondTjlus major} Other vertebrae attributed to the posterior dorsal 

 or lumbar and to the caudal series, by Drs. Mantell and Melville, are referred by 

 Prof. Owen to two additional crocodihan EeptHes under the names of Ceiiosanrus 

 hrevis and G. hrachyurus} 



No portions of the skull of Eadrosaurus were discovered except some small frag- 

 ments of the jaws, represented in Figs. 24-26, Plate XIII. One of these, a portion 

 of the lower jaw, much mutilated externally. Fig. 25, exhibits on its inner aspect. 

 Fig. 24, a series of longitudinal alveolar grooves separated by narrow intervenino- 

 ridges. The other, apparently a portion of the upper jaw. Fig. 26, exhibits similar 

 grooves, but these are bent at an obtuse angle about the upper third of their course. 



As previously mentioned, in association with the bones of Eadrosaurus Foulldi, 

 there were discovered nine teeth, which above all other parts tended to determine 

 the relationship of the fossils. The teeth are so small in comparison with what one 

 would expect to find in company with the other remains, that had they been dis- 

 covered alone, they would perhaps not have been suspected of belonging to Eadro- 

 saurus. They present the same general conformation and peculiarity of structure 

 as those of the Iguanodon, indicating, as in the latter, a vegetable feeding Reptile, 

 one which masticated its food like the herbivorous Mammalia.^ Although amono- 



' Eeport Brit. Assoc, 1S41, p. 91. ^ ibidem, p. 94, 100. 



^ Dr. Mantell, in his work entitled "Petrifactions and tlieir Teachings," p. 228, in an article on 

 the discovery of the Iguanodon, gives the following account: "Soon after my first discovery of bones 

 of colossal reptiles in the strata of Tilgate Forest, some teeth of a very remarkable character particu- 

 larly excited my curiosity, for they were wholly unlike any that had previously come under my 

 observation. The first specimen that arrested my attention was a large tooth, which from the worn 

 smooth, and oblique surface of the crown had evidently belonged to an herbivorous animal, and so 

 entirely resembled in form the corresponding part of an incisor of a large pachyderm ground down 

 by use, that I was much embarrassed to account for its presence in such ancient strata, in which 

 according to all geological experience, no fossil remains of mammalia would ever be discovered • 

 and as no known existing reptiles are capable of masticating their food, I could not venture to assign 

 the tooth in question to a Saurian." 



Dr. Mantell states that "through Mr. Lyell, who was about to visit Paris, he availed himself of 

 the opportunity of submitting the tooth to the examination of Cuvier, who, without hesitation, pro- 

 nounced it to be an upper incisor of a Rhinoceros." This mistake, under the circumstances, was not 

 surprising, as the worn teeth of Iguanodon actually resemble the incisors of the Rhinoceros more 

 than they do the teeth of any other known animal, and at the time of the determination no reptiles 

 were known with teeth adapted to the mastication of vegetable food. 



Cuvier, in the Ossemens Fossiles, Ed. 4, T 10, 199, in reference to the teeth of the Iguanodon, 

 says that "they may possibly belong to a Saurian, but one more extraordinary than any other 

 known. The peculiarity of the teeth consists in their having been worn away as in herbivorous 

 mammals, so that when I first saw a specimen which was much worn, I did not doubt that it was 

 derived from a mammal." He adds, that "it was only after M. Mantell had sent him a series of 

 specimens worn and unworn that he became entirely convinced of his error." 



Dr. Mantell further remarks that "he had previously submitted the tooth and some other specimens 

 to the Geological Society of London, where they were generally viewed as belonging to some large 



