THE STUDY OF FRESH-WATER ANIMALS. 



189 



Crustacea. Water fleas and fresh- water shrimps breathe 

 dissolved air by means of appendages upon certain of their 

 swimming feet. 



Newts. The larvae breathe by tufts of external gills 

 (compare tadpoles) ; the adults by lungs obtaining the air 

 from the atmosphere. 



Locomotor Adaptations. 



The limbs of all aquatic insects should be examined/ 

 Note in particular the following : 



Water Beetles (Dyticus) . Larvae creep on the bottom ; 



Fig. 75. Water Beetle (Dyticus\ 

 In the lower figure the hind limb 

 with its swimming bristles is 

 drawn on a larger scale. 



Fig. 76. Water Bug 

 (Corixa). 



thoracic legs clawed, fringed with hairs for swimming; 

 rise to surface passively. Adults, hind pair of legs longer 



