134 STORY OF THE REPTILES 



blood supply and are thus more active ; but they are 

 not so dark as those of the more agile, more red- 

 blooded birds and mammals. 



We can see from the great surfaces on the bones 

 of the old monsters that there were some tremendous 

 muscles among reptiles in those days (Fig. 62). In 

 such as flew there was a great breast-muscle, like that 

 in birds, which worked the wings, and some had a 

 high ridge or keel on the breast-bone. In all cases 

 the ribs have more muscles in the reptiles than in the 

 mammals. 



The Nerves and Brain 



Many reptiles as well as the amphibians, as already 

 noted, have a great deal of their nervous system out- 

 side of the skull, and hence have small amount of cere- 

 helium — that part of the brain which moves the mus- 

 cles. They therefore die hard after the head is cat off. 

 A turtle is one of these, and is said to be able to live 

 eighteen days after the brain is removed. Its move- 

 ments are then, of course, largely influenced by reflex 

 action. Serpents also are tenacious of life, and squirm 

 long after the brain is destroyed. One with its head 

 off will sometimes turn and strike at any disturbing 

 thing on the body. The author has a friend who 

 nearly had the wits scared out of him by a headless 

 rattlesnake striking his hand as he attempted to pull 

 the rattles from the tail. In this connection it may 

 be well to notice that in some old Dinosaurs there 

 was a hollow expansion in the back -bone near the hips 

 that was much larger than the skull-cavity and held 



