FISHES 1 1 3 



consists of more parts, the membranous layer, or the true 

 bony layer in the gill cover ? (Figs. 21 1 and 21 2.) 



Is the mouth large or small ? Are the teeth blunt or 

 pointed ? Near the outer edge, or far in the mouth ? 

 (Fig. 212.) Does the fish have lips? Are the teeth in 

 one continuous row in either jaw? In the upper jaw 

 there are also teeth on the premaxillary bones. These 

 bones are in front of the maxillary bones, which are with- 

 out teeth. Teeth are also found in the roof of the mouth, 

 and the tongue bears horny appendages similar to teeth. 

 Are the teeth of the fish better suited for chewing or for 



FIG. 212. SKELETON OF PERCH. 



grasping ? Why are teeth on the tongue useful ? Watch 

 a fish eating : does it chew its food ? Can a fish taste ? 

 Test by placing bits of brown paper and food in a vessel 

 or jar containing a live fish. Is the throat, or gullet, of the 

 fish large or small ? 



The skeleton of a fish is simpler than the skeleton of 

 other backboned animals. Study Fig. 212 or a prepared 

 skeleton. At first glance, the skeleton appears to have 

 two vertebral columns. Why ? What bones does the fish 

 have that correspond to bones in the human skeleton ? 

 Are the projections (processes) from the vertebrae long or 

 short ? The ribs are attached to the vertebrae of the trunk, 

 the last rib being above the vent. The tail begins at the 



