M0N0CULD3. 49^ 
black colour, united under a common skin. In 
the female insect the ovarium is generally very 
conspicuous, filling the greater part of the space 
between the shells, above the branchiae or side- 
limbs: the ova are very large in proportion to the 
animal, and the young hatch before their exclusion, 
from the parent. From late observations it ap- 
pears that this animal possesses, in an inferior 
degree, the surprizing property of the genus Aphis, 
viz. that of producing a series of already impreg- 
nated descendants. 
The minute Monoculus quadricornis or four- 
horned Monoculus, must have frequently met the 
eves of every one; since it is not only extremely 
common in every stagnant water, but sometimes 
makes its appearance in that of pumps, wells, k.c. 
and is in consequence occasionally observed in 
water brought to the table. Its size is not greatly 
superior to that of a common mite, but its shape 
is oblong or lengthened, and the female is remark- 
able for the appearance of the ovaria, which are 
attached, on each side the tail, in such a manner 
as to resemble bunches of grapes in miniature: on 
each side the head are two long, jointed arms, re- 
sembling four very long antennae : the tail is long 
and bifid : the general colour of the whole insect is 
white, but it is sometimes seen of a green, and 
sometimes of a reddish cast. 
