482 
THE POLYPHEMUS. 
shelly covering. The yonng are not in the least like their parent, having no shell, no abdo- 
men, and not nearly all their limbs. Each of the antennae is divided into two branches, and 
each of these branches is subdivided at its extremity into three branchlets. 
Another of these wonderful little beings is called the Moina, a genus of which very few 
species are at present known. The color of this species is olive-green, its head is round and 
blunt, and the lower antennae are peculiarly large and muscular at the base. The carapace is 
much smaller behind, and at the end of the abdomen are eight very short spines and two long 
and stout claws. This species is to be found in Europe, especially in ponds of woods, in 
which localities the European microscopic naturalists have detected vast numbers of beautiful 
and even rare creatures that are seldom seen in other places. 
On the back of the Moina is seen a dark mass, which, on account of its shape, is called 
the ephippium, or saddle. This remarkable appendage appears upon the back of the female, 
particularly in summer, and is divided into two capsules, each portion containing one egg. 
The eggs which are placed in this singular resting-place are found to remain unhatched 
through the winter, and are probably defended by this living saddle from the effects of cold, 
just as pistols are sheltered from the inclemency of the weather in their holsters. Probably, 
also, the saddle may serve to protect the eggs from tlie effects of drought, when the pools are 
dried up by a hot and rainless autumn. When the mother moults, the saddle and its contents 
are thrown off, together with the shell, and it is not uncommon to find specimens of the young 
swimming about with a portion of the saddle adhering to them, and looking like young beans 
just sprouting from the earth, and carrying with them the two lobes of the seed from which 
they sprang. 
A very pretty little Entomostracan, belonging to a small sub-family called the Sidinse, is 
called 8 Ida crystallina. In all these beings there are six pairs of feet, the lower an ten use 
have two branches, and a row T of sharp and rather strong filaments springs from the edge of 
the larger branch. In this genus, one branch of the lower antennae has three and the other 
two joints. Though it is occasionally very active, passing through the water with great 
rapidity, it is mostly dull and stationary, having a curious habit of pressing the back of its 
head against some object, and there remaining for a considerable period without moving. It 
derives its specific name of crystalline from its beautifully transparent aspect. 
In the Lynceidse there are two pairs of antennae, the upper being very short, and the 
branches of the lower having three joints. They have five pairs of legs, and one eye, with a 
black spot in front of it. The abdomen is jointed. All the species are rapid swimmers, and 
their food consists of both vegetable and animal matter. 
In the Chydorus, of which one or two European species are known, the body is nearly 
spherical, the lower antennae are very short, and the beak is very long, sharp, and curved 
downwards. The color is olive in the present species, and has a smooth, shining exterior. It 
may be found in ponds and ditches throughout the year. 
The Chydorus sphcBricus , a curious globular-looking creature, is an example of another 
family, called the Polyphemidae, having only four pairs of feet, which are not included in tlie 
shield. Their single eye is very large, and has given rise to the name of Polyphemus, which 
belonged to the one-eyed giant overcome by Ulysses and his companions. The lower antennae 
have two branches — one with four joints and the other with three. In the lower part of the 
carapace there is a large, empty space for the accommodation of the eggs and young. 
An example of the typical genus is the common Polyphemus ( Polyphemus pediculus ), 
found in ditches and ponds. In this creature the abdomen is long and projects from the shell, 
and in the adult the eye is enormously large, seeming to occupy the whole head. There is a 
deep notch or groove in the Polyphemus, seeming to separate the body from the head. It 
appears always to swim upon its back, and uses both the antennae and legs to drive it through 
the water. 
