CHAPTEK YIII 



skeleton generally — back-bone, eibs, skull, mus- 

 cles, nerves, reflex action, tenacity of life, 

 and repair in amphibians 



Skeleton 



The skeleton of the amphibians is interesting for 

 both what it has and what it has not (Fig. 23). The 

 back-bone in the lower forms is much like that in the 

 lower fishes. In some fossil forms the original gristly 

 string around which the back-bone is built still re- 

 mains. In many others the ends of the vertebrae (or 

 pieces of the back-bone) are flattish, or merely a little 

 cupped at both ends — a very primitive state, like that 

 of the sharks. 



In the frog-forms, however, are found the most 

 interesting peculiarities of skeleton. The number 

 of vertebrae are very few — those of the tail being 

 gone as noted ; and instead of many joints in the rear 

 part of the body there is one long, unjointed rod, 

 which runs from about the middle of the back to the 

 rear end of the body. 



Note that the rear legs are attached far back, 

 near the point where the tail should be, and not well 

 up on the back-bone as they are even in man, and that 

 50 



