50 
THE ORDER OR COI.EOPTERA . 
Tribe II. 
PREDACEOUS WATER-BEETLES. 
Carnivora aquatica , Hydradephaga,* MacLeay. 
These insects are distinguished from those of the first tribe by their 
i'eet being fitted for swimming, the two hinder pairs being much flat- 
tened and margined with long hairs or cilia). 
This tribe contains two families. 
A. Antenna; slender, filiform ; hind legs long, and attached to the 
breast far behind the other two pairs DYTisoiniE, 
A A. Antennae very short and peculiar; the three pairs of legs attached 
at nearly equal distances from each other ; middle and hind 
legs very short CtYRlNiDiE, 
Family 111. DYTISOIDiE. 
This family is founded upon the genus Dytiscus, of Linnaeus, derived 
from a Greek word meaning a diver, and given to these insects on ac- 
count of their eminently 
aquatic habits. They are of 
an oval and somewhat flat- 
tened form, and of a brown- 
ish-black color, generally 
with a dull glaucous or sea- 
green tint. In some species 
the thorax is dull yellow, 
either with or without black 
cross-bars. One of their 
most distinctive and easily 
recognized characters is the 
position of the middle legs 
close to the anterior ones, 
leaving an unusually long 
, space between the middle 
Dytiscl'8 : — a, larva of D. margmahs devouring a larva ol 
Ephemera - after Jtiesel : b, pupaof same— after Eye: c, D. and the llilld legs. These 
/ usciventris Say, the detached figure ou the right allowing . 
the grooved elytron of tho female; a, the anterior tarsus of insects are eminently aqua- 
the male, under aide, showing tho suction oups; e , same of 
female— after Riley. tic ail<l pl'OUaceoUH, 1111(1 may 
he supposed to represent th§ sharks and other ferocious aquatic ani- 
mals of the higher classes. 
They have sometimes been found very troublesome in artificial fish- 
ponds, attacking the young gold and silver fishes and eating off their 
* From the Greek faidor—wattr ; and adephagos — ravenous. 
