females are defiitute of this part. The ffrmdure of 
the hind legs, in the whole genus Dytifcus is An¬ 
gularly curious, and finely calculated for their aqua¬ 
tic mode of life; being furnifhed on the interior 
fide with a feries of long and clofe-fet filaments, fo 
as to give a fort of finny appearance to the legs, and 
to enable the animal to fwim with the greateft eafe 
and celerity. It may be added that the female of the 
Dytifcus piceus affords an example of a faculty which 
feems to be exercifed by no other coleopterous in- 
feds ; viz. that of fpinning a kind of web or flattifh, 
circular cafe of filk, which it leaves floating on the 
furface of the water, and in which it depofits its 
eggs : this cafe is terminated on its upper furface by 
a lengthened, conical procefs refembling a horn; 
of a brown color, and of a much ftronger or denfer 
nature than the cafe itfelf, which is white. The 
young larvae, as foon as hatched, make their efcape 
from the envelopement of the cafe, and commit 
themfelves to the water. This curious particular in 
the hiffory of the Dytifcus piceus was firft difeovered 
by Lyonett. 
It is not to be imagined that becaufe the Dytifci 
are fo generally feen in the water, they are therefore 
incapable of living in air: on the contrary, they 
fometimes emerge, and fly about the fields, and thus 
migrate from water to water: but as this happens 
chiefly by night, it is not generally obferved. 
The Dytifcus piceus is an infedr of great ffrength, 
and if incautioufiy handled when taken out of the 
water, will ftruggle in the hand with fo much force 
as fometimes to wound the Ikin with its thoracic 
fpine. 
