618 
ARTICULATA. 
The curious little spiral shells, often seen upon the fronds of sea-weeds, are formed by an animal 
belonging to this family, the Sjnrorhis. 
The Sermellidce, some of which live among the oyster-beds, and often do much mischief by 
the increase of their masses of tubes, also belong to this order. 
EARTH-WOKIIS. 
ORDER a SOOLECmA. 
Of this order, deriving its name from Sholex, a worm, we have well known examples in the 
JEarth-Worms common in gardens and fields. The 
bodies of these animals are of a cylindrical form, 
somewhat pointed at the anterior extremity, and 
usually a little flattened at the tail. The sldn is 
tough, and divided into numerous segments by trans- 
verse wrinkles, and the organs of motion are reduced 
to the form of a double row of bristles, running down 
the lower surface of the body, which, instead of being 
placed, as in the preceding orders, upon prominent 
lobes of the skin, are usually capable of being re- 
tracted within small hollows when not in use. The 
mouth is unarmed, and the intestine runs straight 
through the body. The blood is red. Like the 
leeches, these worms are furnished with ciliated 
canals, which have been supposed to serve as organs 
of respiration ; but their real destination appears to 
be still uncertain. Like the leeches, also, they are all 
hermaphr o dites. 
This order contains two families — the Lumhricidm 
or Earth- Worms, and the Naididce. The former are 
too well known to require extended description ; they 
possess no distinct head, and are quite destitute of 
eyes : their bristles are hooked, and placed in little tufts in pits on the lower surface, whence 
they can be exserted when the animal requires their assistance. They live in holes in moist earth, 
and are said to be predaceous animals, although popular belief charges them with the destruction 
of the roots of plants. It is generally supposed that the earth-worm may be propagated by divi- 
sion ; but this does not seem to be the case. It is said, however, that if it be divided across 
the middle, the part bearing the head will develop a new tail, although the tail part will soon die ; 
and that, if the head be cut off, the body will form a new head ; but it appears that both portions 
never survive this mutilation. 
The power of reproduction of lost parts seems really to exist in the Naididm ; these also 
/""\ propagate by a kind of gemmation, 
one seeming to grow out of the 
other, as represented in the an- 
nexed engraving. Three young 
ones are sometimes seen attached 
to and growing upon the mo- 
ther, at the same time. It ap- 
pears, however, that the tail of 
the original Nais becomes actu- 
ally the tail of its offspring, by which means, as Jones remarks, " this part of the animal may 
be said to enjoy a kind of immunity from death." These animals live principally in the mud of 
fresh-water ponds and rivers. In their form they resemble the common earth-worm ; but their 
bodies are furnished, besides the ventral bundles of bristles, with a series of long spines on 
each side. They generally have two distinct eyes, and the mouth is sometimes armed with a 
long proboscis. 
NAIS. 
