240 PROCEEDINGS OF THE ACADEMY OF 



some six inches in diameter, indicating a humerus of four times the size of 

 that of Lfflaps at least. The claws also of the Megalosaurus are intermediate 

 between those of Leelaps and Poecilopleurum, being less compressed and hooked 

 than in the first. 



Size. — In estimating the length of this reptile we have the lengths of the 

 limbs and tail, and proportions of parts of the jaws to rely on. There is some 

 reason to believe that the lengths of the hind leg and of the tail were similar. 

 In erect animals, as the Kangaroo and Ostrich, the length of the vertebral 

 column anterior to the sacrum about equals the length of the hind limb. In 

 the present form the limb is increased by the greater length of the femur than 

 in either, but is shorter than that of the bird by the abbreviation of the 'meta- 

 tarsals. The proportions would then remain about the same as in the bird, 

 were it not that a head larger than in that class has evidently been borne 

 upon the cervical vertebrfe, more as in the Kangaroo. It appears then that 

 the increased length of the femur in La?laps may be added to the proportions 

 of the Kangaroo, thus giving a nearer equality between the lengths of the hind 

 limb and the body and head together. The length would then be seventeen 

 feet, divided as follows : 



Ft. In. 



Tail 8 6 



Body and necli 6 6 



Head 2 



Total 17 



This is probably the size of the Barnesboro individual, which is in all pro- 

 bability young, as the sacral vertebra; are entirely disunited. The phalange 

 from Mississippi, above described, is very much larger thau any of the former, 

 and may have belonged to an adult animal. In any case it indicates a gigantic 

 reptile of twenty-three feet or more in length. 



The femur of the young individual is as long as that described by Owen 

 (Paheontographica) as belonging to Megalosaurus. As that genus was probJk' 

 bly more bulky anteriorly than Lselaps, its length, as compared with the 

 dimensions of the hind limb, is greater. If, however, it approached Laelaps in 

 proportions, as is probable, the length of thirty feet assigned to it appears too 

 great. In fact it cannot have been larger than the Mississippi, or adult Ltelaps 

 a q u i 1 u n g u i s. 



Thus the original estimate of the lengths of these carnivorous Dinosaurs 

 is still further reduced. Owen accomplished part of this by estimating on the 

 mammalian and rejecting the reptilian type ; the introduction of the avine 

 element places the proportion at about the proper point in respect to the Gonio- 

 poda at least. 



The elevation of the head of Lfelaps would no doubt depend more upon the 

 pleasure of the animal, than in a more quadrupedal form. Nine feet above 

 the o-round is a probable estimate for the young one, and twelve for the adult. 



Movements. — The mind will picture to itself the actions and habits of such 

 strange monsters as the Dinosauria, and in respect to some of the genera there 

 is considerable basis for speculation. 



That monsters walking on two posterior limbs have inhabited the earth, has 

 been familiar to all since the publication, by Hitchcock and Deane, of the 

 histories of the great foot-tracks of the Triassic Red Sandstone of the Connec- 

 ticut valley. Such tracks have been discovered by Jno. Smock, in the same 

 formation, in New Jersey, and by Dr. Chas. Hitchcock in Pennsylvania. Prof. 

 Hitchcock ascribed the tracks described by him to birds. Prof. Agassiz* ex- 

 presses the belief that they were made by vertebrates combining characters of 

 existing classes, perhaps of reptiles and mammals, rather than by birds. Now 

 a carnivorous Dinosaur probably allied to Lalaps, as proven by a portion of 



* Contrib. Nat. Hist. U. S., 1857, vol. i. 



[Oct. 



