AND AYES OF NORTH AMERICA 



113 



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 

 metatarsals. The proportions would (hen remain about the same as in the bird were it 

 not that a larger head has evidently been borne upon the cervical vertebra than in that 

 class, and more as in the Kangaroo. It appears, then, that, the increased length of the 

 femur in Laelaps 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 eighteen feet, divided as follows: 



Ft. 

 8 



Tail, 



Body and neck, 



Head, 



6 



2 



In. 



10 



17 ft. 4 in. 



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

 young, as the sacral vertebra' are entirely ununited. The phalange from Mississippi, 

 above described, is very much larger than 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 lemur of the young individual is as long as that described by Owen (Palaeonto- 

 graphica) as belonging to Mogalosaurus. As that genus was probably more bulky an- 

 teriorly than Laelaps, 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 can hardly have been larger than 

 the Mississippi, or adult Laelaps a quid unguis. 



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 Goniopoda at least, 



The elevation of the head of Laelaps would no doubt depend more upon the pleasure 

 of the animal, than in a more quadrupedal form. Nine feet above the ground is a, proba- 

 ble estimate for the young one, and twelve for the adult. 



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

 sters 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 heen 



AME1U. PIIILOSO. SOC. VOL. XIV.^29 



