CLASS FISHES. 283 



ound the body cavity. The vertebrae of the tail do not 

 >ear ribs. On the dorsal side of each vertebra there is a 

 ittle arch that protects the nerve cord. Compare Fig. 

 09, A and B. 



The muscles of a fish are in segments, as will be seen 

 >y the student on examining a piece of baked fish. These 



FIG. 1 08. Skull of cod (Gadus morrhua). From Nicholson. 



Questions on the Figure. How much of this figure is brain case 

 cranium)! How much is made up of facial bones? Compare this 

 rith Fig. 122, and other references, in this respect. Note how 

 iosely the jaws (p.m., m, and d) are joined to the cranium. 



xtend from rib to rib or from the middle of one vertebra 

 o the middle of the next. The muscles are heaviest about 

 he level of the vertebral column, and thin off along the 

 ides of the body on the ribs. The tail, which may make 

 ip as much as one-third to one half of the body, is a solid 

 nass of muscle acting on the row of vertebras. It is a 

 >owerful organ and when supplemented by the broad 

 ail-fin makes a most effective propeller. 



