118 PISCES (the fish) 



9. The Eyes. 



(1) How many? 



(2) Location? 



(3) Parts of eye present as compared with your own? 



(4) Parts wanting as compared with your own? 



(5) Why these differences? 



10. The Ears. 



(1) Do you find any evidences of external ears? 



(2) If not, why not? 



(3) Does the fish hear? State your proof. 



11. The Mouth. 



(1) Size? 



(2) Shape? 



(3) Position? 



12. The Gill Covers. 



(1) Position? 



(2) Use? 



13. The Gill Openings. 



(1) Position? 



(2) Use? 



(3) Number? 



14. The Scales. 



(1) Number of rows from dorsal to ventral edge? 



(2) Number in one row from side of head to caudal fin? 



(3) Estimate the total number of scales on the entire fish. 



(4) How are the scales fastened into the skin? 



(5) Are the scales naked or covered with a membrane? 



(6) Is the pigment in spots or is it uniformly distributed? 



Use of the pigment? 



(7) Are the scales ctenoid or cycloid^ ? 



(8) Examine a scale with hand lens or microscope. Sketch 



one (enlarged five or ten times) to show its structure. 



15. The Lateral Line. 



(1) How do the scales of the lateral line differ from those 



of other parts of the body? 



(2) Use of lateral line? 



16. Sketch. Turn the specimen with its unmutilated side 

 toward you and sketch a side view of it, locating the mouth, 



iSee Part II, "Economic Zoology," Figs. 173, 174. 



