COLEOPTEIU — BEETLES. 231 



they cany with them a small globule of air, some- 

 thing like that of the Water Spider, which, as they 

 descend, glitters like a granule of quicksilver. 

 Rosel succeeded in rearing a brood of larvae of the 

 Whirligigs, from eggs found upon the leaves of 

 aquatic plants ; an experiment that might be tried, 

 with still better chance of success, in our Insect 

 Home; and much information upon the subject 

 might be gathered by such as wish to try the ex- 

 periment, from the minutely detailed account given 

 by Modeer of all their successive transformations. 



The Hydrophilidce have been separated from the 

 Dytiscidce on account of certain characteristics which 

 I have not space to describe here. I can only 

 call to the collector's recollection that Hydro- 

 philns JPiceus is the largest and handsomest of the 

 Water Beetles, and, as he is comparatively harmless, 

 he may be kept in a tank without fear of his 

 injuring the other inmates. The eggs of Jlydro- 

 philus Piceus are gummed together by a substance 

 spun hy the female, by which means fifty or sixty 

 are attached together, forming a mass something 

 like a small turnip, which is always secured to 

 some aquatic plant. When the eggs are hatched 

 the shells still remain gummed together, and the 

 mass having hecome detached from its anchorage, 



