HYDROPHIL'. 
98 
that the female of the Hydrophilus piceus affords 
an example of a faculty which seems to be exer- 
cised by no other coleopterous insect; viz. that 
of spinning a kind of web or flattish circular case 
of silk, which it leaves floating on the water, and 
in which it deposits its eggs. This case is ter- 
minated on its upper surface by a lengthened 
conical process resembling a horn, of a brown 
colour, and of a much stronger or denser nature 
than the case itself, which is white. The young 
larvm, as soon as hatched, make their escape from 
the envelopement of the case, and commit them- 
selves to the water. This curious particular in 
the history of the Hydrophilus piceus was first 
discovered by Lyonett. 
The Hydrophilus carahoides is a species measur- 
ing about three quarters of an inch in length, and 
is of a polished black colour, and of an oval shape. 
Like the former, it inhabits stagnant waters, where 
its highly curious larva, admirably figured in the 
works of Roesel, may not unfrequently be found: 
it is fringed along the sides with numbers of sepa- 
rate plumes or feather-formed branchiie. 
The genus Hydrophilus, like that of Dytiscus, 
has been greatly increased by the persevering re-, 
searches of modern entomologists. Mr. Marsham 
enumerates twenty-eight British species. 
It may be added that the Hydrophili, like the 
Dytisci, sometimes emerge from the waters, and 
fly about the fields, and thus migrate occasionally 
from water to water; but as this happens chiefly 
by night, it is not generally observed. 
