NATURAL HISTORY. 1] 
served it to be replaced by another, which, how- 
ever, seldom attains the size of the former. 
These larvee feed on almost every other kind, 
and, in their turn, are devoured by the larger 
water-beetles (Dytiscus marginalis and semistri- 
atus). 'Their favourite food is the larve of the 
ephemera* and gnat. On the other hand, even 
when kept without food, they refuse monoculi, 
preferring to feed on each other. From this 
propensity, if confined in separate vessels for a 
few days, and afterwards put together, the most 
fierce and obstinate combats ensue. In these 
engagements the little animals display all the 
courage, skill, and caution of two well-trained 
pugilists, turning about with extended jaws, 
till a fit opportunity occurs for attack. Their 
courage is such, that I have seen a small one seize 
another twice its size, and hold it for several 
seconds. When, however, they are of equal 
size, and exceedingly pressed by hunger, the con- 
test will be continued for several minutes, and, 
to the lovers of such sports, will be found not 
inferior to any; and when viewed on the screen 
of a solar or gas microscope, several spectators 
can witness it at the same time, and make their 
observations and remarks as the battle proceeds. 
* An elegant species of this larva is figured in the ‘‘ Micro- 
scopic Illustrations.’’ 
