OUR FRESHWATER ENTOMOSTRACA. 
45 
The body is contained within a delicate shell composed of two 
valves, soldered together, as it were, on the back, and open on 
the anterior margin, through which the feet and tail can be 
protruded at pleasure. Posteriorly these valves are prolonged 
to an acute point. The head is bold, and projecting from the 
rest of the body, and the black spot on its forehead is the eye. 
This organ is furnished with powerful muscles, so arranged as 
to allow it to possess a semi-rotatory motion upon its axis, and 
is compassed about with numerous glassy-looking or crystalline 
lenses. The two large branched organs projecting from the 
head are called the large antennae ; and it is by means of these 
organs that the water-flea is able to propel itself through the 
water. The mouth is situated near the base of the beak, and is 
furnished with two mandibles and one pair of jaws. The broad 
dark streak running down through the body is the stomach, 
which we see curved at its upper part into a complete arch, and 
then running nearly straight downwards through the body till 
near its extremity, when it curves suddenly again in an upward 
direction. This part of the animal and the remaining portions 
of the body can be seen quite clearly and distinctly through the 
carapace or shell. The body proper terminates in a broadisb 
plate, which ends in two horny-looking hooks ; and this part 
forms what is called the tail, and, with the greater part of the 
body, can be extruded beyond the valves at pleasure. The legs 
are five pairs in number, and even when the little creature is at 
rest, these organs may be observed to be in constant motion, 
which communicates an undulatory motion to the water, esta- 
blishing a regular current which carries the particles destined 
for its food towards the mouth. The chief use, however, of 
these organs is for respiration, and for this purpose they are 
well adapted by their having a branchial plate attached to them 
furnished with long plumose setae or bristles, and which answers 
the same purpose as the gills of the crabs and lobsters, &c. 
In the females (fig. 5), the ovaries are internal, are placed 
along the sides of the stomach, and show their situation by the 
eggs appearing there in the shape of small round pellucid 
globules. 
In this pool in which we have found these daphniae, they are 
all clear and transparent ; but at times, and in other situations, 
they become of a red colour, and, when very numerous, as they 
sometimes are, they impart, at first glance, a red hue like blood 
to the whole pond in which they are observed. When this was 
first noticed, it was looked upon as a bad omen, and some 
calamity was prophesied as sure to follow. I have often seen 
this phenomenon in horse-ponds and such like places, and have 
often been surprised to see suddenly large patches of the pond 
become of a ruddy hue, like as if a quantity of the red rust of 
