47° 



PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



RHIZOPODS. 



Many rhizopods have no hard parts, but others, 

 especially Foraminifera and Radiolaria, form calcareous 

 or siliceous skeletons of exquisite beauty and com- 

 plexity. They form the most beautiful objects under 

 the microscope. These skeletons are also very charac- 

 teristic of the various orders (Fig. 331). 



