184 THE STORY OF REPTILE LIFE. 



of the Diplodocus just described we have almost 

 convincing proof of this. The limbs of this 

 species, it is interesting to note, were of the same 

 type as those of the Atlantosaurus and Bronto- 

 sauruSj pillar-shaped and short-toed, that is to 

 say, they resembled the limbs of the Elephant, 

 Hippopotamus and Rhinoceros in the main feat- 

 ures, and these, it is to be noticed, all have ex- 

 tremely heavy bodies. Accordingly this type of 

 limb has been adopted as most suited to bear the 

 strains imposed thereon. 



The existence of limbs of this type in an ex- 

 clusively aquatic animal is an extremely inter- 

 esting feature, and shows that this mode of life was 

 adopted long after the limbs had become adapted 

 to the requirements of a terrestrial life, as in the 

 case of the Hippopotamus among the Mammalia. 

 The latter, it is to be remarked, is an expert 

 swimmer, though we would not gather as much 

 from the shape of the legs ! Possibly, like the 

 Hippopotamus, these ancient reptiles passed a 

 certain amount of time on shore, and hence the 

 need of preserving the terrestrial form of the 

 limbs. 



Among the bipedal types we have equally 

 gigantic species. As an example we may select 

 the celebrated Iguanodon bernissartensis, repre- 

 sented as in life opposite. Like the four-footed 

 types, some of these huge bipeds are believed 

 to have been aquatic, on account of their 

 great size. Although there is much to be 

 said in support of this view, there yet seems 

 room for doubt as to whether this aquatic 

 habit was as universal as the hypothesis de- 



