GIANT LAND REPTILES OR DINOSAURS. 131 



North America, and even as far north as Behring 

 Strait. Some of the smaller species, like those found 

 in the Lithographic limestones of the Continent and 

 in the United States, probably took considerable leaps 

 with their long hind legs, and must thus have re- 

 sembled the smaller kangaroos of Australia. 



Briefly summing up the result of the foregoing 

 observations, we find that the Giant Land Eeptiles 

 may be divided into three great primary groups pre- 

 senting the following distinctive features. In the first 

 group, as represented by the Iguanodon, the teeth were 

 adapted for grinding, and had compressed crowns, orna- 

 mented with ridges on the outer side ; the limb-bones 

 were hollow ; the pelvis was bird-like ; and the mode 

 of progression was bipedal. In the second group, as 

 exemplified by the Hoplosaur, we have nearly or quite 

 the largest known land animals; their teeth were 

 spoon-like, and adapted for vegetable food ; the limb- 

 bones were solid throughout ; the pelvis was not very 

 unlike that of a crocodile ; and the mode of progres- 

 sion was quadrupedal. Finally, in the third group, 

 of which we took the Megalosaur as our type, the 

 teeth and claws were adapted for capturing and 

 devouring living prey ; and although the pelvis ap- 

 proximated to the crocodilian plan, yet in the structure 

 of the leg and ankle these reptiles (in which the limb- 

 bones were hollow) made a closer approximation to 

 birds than is presented even by the Iguanodon. 



The above-mentioned remarkable variations of struc- 

 ture presented by the members of the three foregoing 



