HADROSAURUS. 83 
general character ascribed to the vertebrae of Jyuanodon; those of Hadrosaurus are 
totally different. 
The convexo-concave vertebre attributed to the cervical series of Iyuanodon by 
Drs. Mantell and Melville, are referred by Prof. Owen to a Crocodile under the 
name of Streptospondylus major.’ Other vertebre 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 crocodilian Reptiles under the names of Cetiosawrus 
brevis and C. brachyurus.” 
No portions of the skull of Hadrosaurus 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 intervening 
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 Hadrosaurus Foullii, 
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 Hadro- 
saurus. They present the same general conformation and peculiarity of structure 
as those of the Jyuwanodon, indicating, as in the latter, a vegetable feeding Reptile, 
one which masticated its food like the herbivorous Mammalia.’ Although among 
* Report Brit. Assoc., 1841, p. 91. 2 Tbidem, p. 94, 100. 
3 Dr. Mantell, in his work entitled “Petrifactions and their Teachings,” p. 228, in an article on 
the discovery of the Zguanodon, 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 Zguanodon, 
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 
