Reptiles. 



6449 



digging, went down along its edge, six or seven feet, through a small hed of shells, to 

 where the bones had been exhumed ; and here, sure enough, were the rest of them un- 

 touched; a hind thigh-bone 40 inches long, a shin-bone 35 inches long, a splint-bone 

 to match, an arm-bone 19 inches long, with one of the fore arm-bones to match, dozens 

 of vertebra?, neck, back and tail, huge masses of the pelvis and shoulder-blade, some 

 few bones of the foot or toe-joints, and a tooth, — all lying upon a second bed of shells : 

 as the teeth were all-important and were liable to be disturbed, the soil of the pit was 

 re-dug and carefully examined, and with great success. When Dr. Leidy was in- 

 formed of the discovery, he and some other Members of ihe Academy, Mr. Lea and 

 Dr. Le Coute among them, saw nothing in it but the common occurrence of Mastodon 

 or mammoth bones entombed in an ancient bog. On going to the rooms, to which 

 they had been with care conveyed, he recognised at a glance the evidences of their 

 reptilian character: since then, weeks of patient adjustment and study have resulted 

 in the noble lecture which he gave us last evening upon the Hadrosaurus Foulki of 

 the green sand of America. He first enumerated the indications of reptilian form ; 

 the thigh-bone ossified, not like the mammals, from half-a-dozen centres, but from 

 one single centre, as in the iguana, alligator, &c, and furrowed at the ends with the 

 large blood-vessels of reptile-joints, instead of being smooth as in all mammalians. 

 The whole form of the bones was different, and the vertebrae 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, thiu, deep 

 reptilian tail. The teeth were also reptilian, and not carnivorous, like the crocodile's, 

 but herbivorous, like the iguana's, and most curiously shaped and set. The creature 

 was evidently of unimagiued 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 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 anatomist would have hesitated to assign them to animals of 

 different kinds, or at least to different individuals; but the animal which this one 

 most resembles, discovered in an English rock of the same age by Dr. Mantell, shows 

 the fore and hind legs equally dissimilar. The fact, no doubt, is, that we have here 

 the relics of a kangaroo-like alligator, of more than mammoth size, living near the 

 great tertiary rivers and lagoons, and feeding on the vegetation, as it sat erect on its 

 vast hind legs, supported by its tail. To get at its length, Dr. Leidy took the 

 number of neck and back vertebrae common to all kinds of reptiles, and averaged 

 the number of tail vertebrae between the hundred in a tail of the iguana and 

 the twenty or thirty in the tail of the crocodile, and thus fixed the probable 

 length of the whole creature at 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 tessellated wall around the mouth as to make a formid- 

 able cutting and grinding apparatus. * * * * The enormous size of this 

 creature was exposed by a comparison of its thigh-bone with <me of a mammoth in the 

 Academy collection, only two-thirds as long ; but what was the astonishment felt to 

 see the Doctor lift from the table a fragment of a thigh-bone nearly half as long again, 

 describing its reception some years ago from the same district, and its being stowed 

 away as an uncharacteristic, and therefore, for the time being, a worthless specimen, 

 since there were no more perfect bones of the same shape with which to compare it 

 and determine its relations. This is one of many examples constantly afforded by 

 XVII. T 



