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the water and somewhat resemble the snail in appearance. The body is thickly set 
with fine hairs, which are kept in continual motion, and thus enable the creature 
to shift its position. The second order, the Zrematodes, are furnished with suckers, 
and live as parasites, mostly on fishes, but also in the intestines of other animals. 
The third order, the Cestodes, or tape-worms, are very long and flat, and in their 
perfect state consist of a large number of segments, the head being furnished with 
hooks and suckers. Almost all of them live as parasites in the intestines of animals. 
Their propagation is effected in a twofold manner: by the separation of the posterior 
segments, which speedily develop into a perfect individual, and by eggs. These 
eggs however do not produce the perfect worm, but an intermediate larva form, or 
hydatid, which lives in the flesh or in the organs of the animal, and only developes 
into the perfect tape-worm on reaching the intestine. — 
The Echinodermata are exclusively marine animals, and present great varieties 
of form, the skin being however in all cases beset with spines, warts or other ex- 
crescences. They have a plainly discernible mouth, which is generally situated on 
the lower side, and are also furnished with a number of suckers, by using which 
they are enabled slowly to shift their position. Their food consists of mussels and 
other marine animals. The Holothurie, which constitute the first group, have an 
oblong, coriaceous body, open at both ends, the mouth being situated at the anterior 
extremity and surrounded by very complicated branched tentacula. There are double 
rows of suckers along the whole length of the body. The next group, the Echinoidea, 
or sea-urchins, contains a number of genera, which do not however show any very 
great variety of form. The body is round in shape and consists of from four to six 
plates covered with spines of different lengths, between which the suctorial feet are 
protruded. The mouth, which is furnished with a powerful masticatory apparatus, 
is situated on the lower side, which is somewhat flattened. 
The Asteriw, or Star-fishes, are found in two varieties — the scutellated, and 
the radiated, some descriptions of the latter appearing to consist of arms and nothing 
else. These arms, which vary from five to twelve in number, are grooved with a 
longitudinal furrow on their lower side, the furrow being pierced laterally with small 
holes through which pass the feet or tentacula, each of which terminates in a little 
suctorial disc. By alternately lengthening and shortening these numerous little 
organs, and fixing them by means of the terminal disc, a slow sort of locomotion 
is attained. The upper side of the star-fish is generally gorgeously colored, and is 
covered with short spines and calcareous warts and excrescences. The Crinoidea, 
although of but rare occurrence in our modern seas, were one of the most widely 
diffused forms of animal life in the earlier ages of the world, as is evidenced by the 
countless myriads of their remains, which fill so many limestone beds and compose 
vast strata of marble extending over large tracts of country in the Northern hemi- 
sphere. They grow attached to the bottom of the sea, and consist of a long, slender 
stem bearing a body of varying shape, furnished with a number of delicate arms, 
the whole forming a beautiful flower-like animal. — 
No general distinctive marks can be quoted for the group of the Celenterata, 
which embraces the Sea-blubbers and the Polypi. The only feature of their internal 
structure that need be mentioned is that the intestine does not consist of a separate 
canal, but is connected with every part of the body by means of a diffused tubular 
system. The Meduse, or Sea-blubbers are soft, gelatinous creatures, with a hemi- 
spherical body resembling a mushroom or umbrella in shape, and from the under 
side of which a number of tentacular cirrhi depend. These cirrhi are endowed with 
the property of stinging or numbing any creatures with which they are brought into 
contact, and are used for the purpose of securing their prey. They float about in 
the sea near the surface, and are seen in vast numbers in the warmer season of 
the year, many varieties being endowed with the faculty of producing a phospho- 
rescent glow. Most of the Sea-blubbers have to pass through a larva stage after 
emerging from the egg. 
The Polypi differ from the Meduse in living for the most part fixed to one 
spot. Some of them, like the Sea-anemones, or Actinia, pass a solitary existence, 
attached to some rock in the sea, while others, such as the coral, live united in vast 
colonies. The aperture which serves both for mouth and vent is situated at the top, 
