POND LIFE. 117 



almost any pond. If you can obtain specimens of the 

 larger ones, they will be best for the purposes of study. 



Some specimens should 

 be kept alive in aquaria for 

 a study of their habits, and 

 some should be killed and 

 pinned for a study of their 

 structure. 



Place the pinned speci- 

 mens when not in use in ^ 



. Fig. 93. Fig. 94. 



your collection under a 



copy of the following label and immediately after the 



whirligig-beetles : — * 



Family Dytiscid^ (Dy-tis'ci-dae). 

 The Predaceous Diving-beetles. 



Whenever convenient to do so, watch the diving- 

 beetles and learn all you can regarding their habits. 

 Make a memorandum of whatever you learn ; the 

 hints given on page 1 14 for the study of the whirligig- 

 beetles will be useful here. As these diving-beetles 

 are predaceous, they may be fed with other insects 

 or bits of raw meat. If properly cared for, they can 

 be kept alive in aquaria for a long time, even several 

 years. 



The Structure of the Predaceous Diving- 

 beetles {School Work). — Select for study specimens 

 of the largest species of predaceous diving-beetles in 

 your collection and observe the form of the following 

 parts : — 



* No effort is made in these outlines to indicate a natural sequence 

 of the families studied. It will be sufficient for the purposes of begin- 

 ners to place each family under the order to which it belongs, placing 

 first those studied first. 



