I04 A GUIDE FOR THE STUDY OF ANIMALS 



how the ends of the cartilaginous rays keep the membrane 

 from tearing. 



Investigate the scales as to their arrangement, number, 

 and size. Remove a small patch of scales along the 

 lateral line to find how they are attached, where the fish's 

 color is situated, and how access to the .sensory organs of 

 the line is permitted. Examine a scale under the micro- 

 scope. 



Observe the eyes and identify the parts similar to those 

 of the human eye : lid, lash, tear-duct, cornea, iris, and 

 pupil. 



In front of and between the eyes, find the nostrils. By 

 means of a bristle determine whether these are connected 

 and whether they do or do not open into the mouth or 

 the throat. 



Questions. 



1. Make a list of the fins, classifying them according to 

 their structure. 



2. Bearing in mind the differences in structure and 

 consequent action, — what can you say regarding the 

 adaptation of the several fins for protection } for rigidity 

 or flexibility in locomotion .' 



3. State how much of the body is covered with scales, 

 and where the largest and the smallest ones are found. 



4. How are the scales arranged with reference to each 

 other ? What benefit is derived from this in protection ? 

 in locomotion .' If you have noticed any mucus or slime 

 upon the body, state its use. 



5. Do the scales or the skin bear the pigment .'' Give 

 the color pattern of the kind of fish used in class. How 

 would this be useful to the fish in its natural home } 



6. Describe the structure of a scale and state how it is 



