170 



FIRST BOOK OF ZOOLOGY. 



Cavity below, contain- 

 ing lun^s, heart, 

 stomach, etc. 



FIG. 151. A VERTEBRA AND A PATE OF ETBS, FROM A CAT C S, Cavity for Cerebro-spinaJ 



Cord. 



152. If we compare the hind-leg of the salamander with 

 our own leg, we shall find essentially the same arrangement 

 of parts, namely : the leg bending at a joint in its middle, or 

 the knee-joint, and below this joint another one called the 

 ankle-joint. In that portion of the leg above the knee-joint 

 there is one long bone called the femur which joins or articu- 

 lates with the pelvic arch. In the leg below the knee-joint 

 there are two long bones side by side, called the tibia and 

 fibula. In the ankle-joint there are a number of small 

 bones closely packed together ; these are called the tarsal 

 J)ones^ and together form the tarsus. In the body of the 

 foot there are several bones upon which the toes rest, and 



