There are as many as twelve known species of the Water Flea. That
represented in the engraving is extremely common, and forms a most
interesting object for the microscope. We have availed ourselves of Mr.
Pritchard’s popular description of this curious creature.
“The Author of Nature, to whom all things are alike easy of execution,
as if intending to teach man a lesson of humility, and that no part of
creation, however minute, is beneath his consideration, has conferred
on these animals, that are barely perceptible to our unassisted vision,
more elegance and variety of form, more richness in their colouring,
and more beauty and exquisite finishing, than on the whale or the
elephant, which mainly excite our admiration, by the magnitude of the
mass of living matter they present to us.
[Illustration: _Cyclops quadricornis._
(Fig. 1, highly magnified; fig. 2, natural size.)]
“These little crustaceous animals may be found at all seasons of the
year, near the surface of the water; they are, however, most abundant
in July and August. I have collected great numbers of them on a warm
day in the latter month, with a small cloth net, immersing it about an
inch below the surface. They are mostly colourless in ponds covered
with herbage, but in small collections of rain water, on a loamy soil,
are of a fine rich colour.
“The body of this creature is covered with crustaceous or shelly
plates, which overlap each other, and admit both of a lateral and
vertical motion between them. Their ends do not meet on the side, but
have sufficient space between them for the insertion and play of the
organs of respiration. The rostrum, or beak, is short and pointed: it
is a prolongation of the first segment which forms the head. A little
above the beak, a single eye is imbedded beneath the shell, of a dark
crimson colour, nearly approaching to blackness. The true form of this
organ it is difficult to determine. Mr. Baker gives it the shape of two
kidney-beans placed parallel to each other, and united at their lowest
extremities. When viewed laterally, it appears round, while in some
other positions it is square.”
The eggs are curiously placed in two bags, presenting an appearance
similar to clusters of grapes, and of considerable magnitude, compared
with the size of the animal. These egg-bags are seen in the engraving,
(which represents a female,) projecting from each side of the hinder
portion of the shell. The centre of each egg is of a deep opaque
colour, which in some specimens is green, in others red.
The young of the Cyclops, when first excluded from the egg, are
extremely minute, and so different from the mother, that Müller has
described them as forming two distinct genera.