220 THE WORLD OF LIFE 



the most singular of these is the Brontosaunis, the skeleton of 

 which is here represented. It is said to have the smallest head 

 in proportion to the body of any vertebrate animal. Pro- 

 fessor O. C. Marsh, who discovered it, states that the entire 

 skull is less in diameter or weight than the fourth or fifth 

 neck vertebra, while the brain-cavity is excessively small. He 

 says : '^ The very small head and brain indicate a stupid slow- 

 moving reptile. The beast was wholly without defensive or 

 offensive weapons or dermal armour. In habits it was more 

 or less amphibious, and its remains are usually found in local- 

 ities w'here the animals had evidently become mired." 



A creature nearly as large was the Cetiosaurus leedsi, from 

 the Oxford clay near Peterborough, of which the left hind limb 

 and the larger part of the tail are mounted in the British 

 Museum. It measures 10 feet 6 inches high at the hip, and 

 must have been nearly 60 feet long. Still larger was the Amer- 

 ican Atlantosaurus immanis, of w^hich only fragmentary por- 

 tions have been obtained; but a complete thigh-bone, 6 feet 

 2 inches long, is the largest yet discovered. It was found in 

 the Upper Jurassic strata of Colorado, U.S.A. 



The largest complete skeleton is that of the Diplodocus car- 

 negii, now w-ell known to all who have recently visited the 

 British ^Natural History Museum, where a model of it is 

 mounted, as shown in the photographic picture of it here repro- 

 duced. It is SO feet in length, both neck and tail being enor- 

 mously long in proportion to the body. It is supposed that it 

 would have been unable to walk on land except very slowly, 

 and that it inust have lived chiefly in the water on juicy water- 

 weeds, which its very weak teeth, as shown in the above figure 

 of the skull, would alone have been such as it could graze on. 

 The very long neck would have enabled it to gather such food 

 from moderately deep water. The brain occupied the small 

 space between and behind the eyes (Fig. 58). 



These huge reptilian herbivora, feeding in marshes, lakes, 

 or shallow seas, w^ere preyed upon by the numerous crocodiles 

 which lived throughout the same j)criods and are everywhere 



