THE EARTH-WORM, 579 
ANNULATA, 
A NEw class of animals now comes before us. These creatures are 
technically called ANNULaTA, or sometimes ANNELIDA, on account of the 
rings, or annuli, of which their bodies are composed. ‘Lhey may be dis- 
tinguished from the Julidz by the absence of true feet, although in very many 
species the place of feet is supplied by bundles of bristles, set along the sides. 
The resp ration is carried on either by means of external gills, internal sacs, 
or even through the skin itself. In most of the Annulata the body is long 
and cylindrical, but in some it is fattened and oval. The number of rings is 
very variable, even in the same species. 
The group of worms which come first on our list is remarkable for the 
architectural powers of its raembers. In order to protect their soft-sk'nned 
body and delicate gills, they build for themselves a residence into which they 
exactly fii This residence is in the form of a tube, and in some cass, as in 
the Serpule, is of a very hard sheily substance, and in some. as the Terebella 
is soft and covered with grains of sand and 
fragn ents of shells. 
The beautiful SERPULA is now very familiar , 
to us, through the medium of marine aquaria, 
its white shell, exquisite fan-like branchize, and 
brilliant opercu um, having lived and died in 
many an inland town where a li ing inhabitant 
of the ocean had never before been seen. The 
Serpula is able to travel up and down its tube 
by the bundles of bristles which project from 
the rings along the sides, and to retract itself 
with marvellous rapidity. It has no eves, and 
yet is sensible of light. For example, if a 
Serpula be fully protruded, with its gill-fans Serpula contortuplicala, 
extended to their utmost, and blazing in all its 
scarlet and white splendour, a hand moved between it and the window will 
cause it to disappear into its tube with a movement so rapid that the eye 
cannot follow it. The gills, whose exquisitely graceful form and delicate 
colouring have always attracted admiration, are affixed 10 the ncck, as, if they 
were sct at tle opposite extremity of the body or along the sides, they would 
not obtain sufficient air from the small amount of water that could be con- 
tained in the tube. The beautiful scarl.t stopper ought also to be mentiored, 
Each sct of gills is furnished with a tentacle-lik appendage, ore of which is 
small and thread like, and the other expanded at its extremity into a conical 
operculum or stopper, ma ked with a number of ridges, which form a beauti ul 
series of teeth around its circumference. The footstalk on which this stopper 
is mounted is a litt!e longer than the gills, so that when the animal retreats 
into its tube the gills collapse and vanish, and the entrance of the tube is 
exactly closed by the conical stopper. 
THE fami'y of which the common EARTH-WORM is avery familiar example 
is distinguished by the ringed body without any g lls or feet, but with bristles 
arranged upon the rings for the purpose of progression. 
In the well-known Earth-worm, the bristles are short and very stiff, and are 
eight in number on each ri¢g, two pairs being placed on each side; so that, 
in fact, there are eight longitud nal rows of bristles on the body, four on the 
sides and four below, which enable the creature to take a firm hold of the 
ground as it proceeds. Except that the worm makes use of bristles, and the 
snake of the enges of its scales, the mode of progress is much the same in 
both cases. The whole body of the creature is very elastic, and capable of 
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