336 ANNUAL OF SCIENTIFIC DISCOVERY. 



They differ from the others in the extraordinary degree of development of 

 the medium carina of the crown. These teeth also exhibit the impress of 

 successors holding the same relative position with one another as in the lower 

 teeth. 



At the meeting of the Academy above referred to, Dr. Leidy stated, that 

 he had determined the bones to have belonged to a huge herbiverous sau- 

 rian, which was closely allied to the Iguanodon; the genus, however, w:is 

 different, and he proposed for it the name hadrosaurus designating the 

 species from the discoverer of the bones, Hadrosaurus Foulkii. Dr. Leidy 

 then proceeded to point out the reptilian characters recognized in the bones 

 in question: The thigh-bone ossified, not, like the mammal's, from half a 

 dozen centres, but from one single centre, as in the iguana, alligator, etc., 

 and furrowed at the ends with the large blood vessels of reptile joints, in- 

 stead of being smooth, as in all mammalians. The whole form of the bones 

 was different from that of the mammalia, and the vertebra; of the tail were 

 armed above with the backward leaning processes, and below with the 

 loosely shaped, and likewise backward leaning spines, which characterize 

 the powerful, long, thin, deep reptilian tail. The teeth were also reptilian, 

 but not carniverous, like the crocodile's, but herbiverous, like the iguana's, 

 and most curiously shaped and set. 



The creature was evidently of huge dimensions. Its hind-leg bones, when 

 put together, would reach seven feet, upon which the pelvis and back-bone 

 and upper skin would still go on, making it nine or ten feet high upon the 

 haunches. On the contrary, the fore legs were so disproportionately short, 

 that, had they been found at a different time or in a different place, no anat- 

 omists would have hesitated to assign them to animals of different kinds, or 

 at least to different individuals. 



"This great disproportion of size," says Dr. Leidy, "between the fore and 

 back parts of the skeleton, leads me to suspect that the Hadrosaurus may 

 have been in the habit of browsing, sustaining itself, kangaroo like, in an 

 erect position on its back extremities and tail. As we. however, frequently 

 observe a great disproportion between the corresponding parts of the body of 

 recent and well-known extinct saurians, without any tendency to assume 

 such a position as that mentioned, it is not improbable that Ilddrosfmru.-i 

 retained the ordinary prostrate condition, progressing in the manner which 

 has been suspected to have been the case in the extinct batrachian of an 

 earlier period, the Labyrinthodon." 



" If we estimate the number of vertebra? of the trunk of Hadrosaurus to 

 have been the same as in the recent Crocodile and Iguana, the number of 

 sacral vertebra? to have been the same as in the Iguanodon, and the number 

 of caudal vertebra to have been fifty, the whole number of vertebra? would 

 have been eighty. A calculation of the length of the specimens of vertebra? 

 in our possession, Avith a proper allowance of separation by invertebral fibro- 

 cartilages, and an addition of two and a half feet as an estimate of the length 

 of the head, would give, as the total length of the animal, about twenty-five 

 feet." 



Its tail must have been three feet deep ; its neck thin, and its head no 

 doubt small. Its teeth are but two inches long, but set in such a tessalated 

 wall around the mouth as to make a formidable cutting and grinding appa- 

 ratus. 



Hadrosaurns was most probably amphibious; and though its remains 

 were obtained from a marine deposit, the rarity of them in the latter leads 



