CHAPTER III 



THE FROG (continued) : THE SKELETON 



IF you have followed the description given in the preced- 

 ing chapter with a frog before you, testing every statement 

 as you proceeded by reference to the specimen, you will 

 now have a very fair notion of the general build of the 

 animal. The next thing to do is to study its various parts 

 in somewhat greater detail. 



As the bones and cartilages form the framework on which 

 all the other parts are supported, it is convenient to begin 

 with them. You may study them on a prepared skeleton, but 

 a far better plan is to make a skeleton for yourself as 

 directed on p. 53. 



Parts of the Skeleton. The skeleton consists of the 

 following regions :- 



1. The skull (Figs* Sand 9) : a complex mass of mingled 

 bone and cartilage, enclosing the brain and the organs of 

 smell and hearing, and supporting the upper jaw. Connected 

 loosely with the skull, but really forming part of it, are the 

 lower jaw and the tongue cartilage. 



2. The vertebral column or backbone , consisting of nine 

 movably united pieces, the vertebra (Fig. 8 v. i V.Q), and 

 of a long bony rod, the urostyle (UST), representing a num- 

 ber of fused vertebrae belonging to the tail-region of the 

 tadpole. 



D 2 



