52 



THE AQUA VIVARIUM. 



any description, as it maybe known by its size. 

 The female possesses the faculty of spinning a 

 gummy envelope for its eggs, which it attaches to 

 water-plants ; this nest is nearly an inch in breadth, 

 and contains fifty or sixty eggs. The young, when 

 hatched, feed upon small aquatic Crustacea and 

 mollusca. When taking their prey, they bend back 

 their heads so far that they make use of their backs 

 as a table to support their food. The larva, when 

 full grown, creeps out of the water, burrows in an 

 adjacent bank, where it remains for some days 

 as a pupa, and at last comes forth as a perfect 

 beetle. 



FIG. 11. 



FIG. 12. 



Another family of Water Beetles are the Dyti- 

 cidce. The best-known form of these insects is. the 

 Dyticus marginalis. This is much more common 

 than the last beetle, and the male and female 

 may be taken in most of our fresh- water ponds. 

 (Figs. 11 and 12.) Their structure is exceedingly 

 interesting, and those who maintain an Aqua- 

 vivarium for instruction rather than amusement, 



