ON ANNELIDA. 
73 
larly in the Indian* all the other genera have some species in 
all seas. We may observe* however* that the largest species 
come to us from the Indian seas. 
It is in general on the shores of the sea, in the midst of 
thalassiophytes* in the anfractuosities of the madrepores* of 
rocks, in the sand, and particularly in mud, that the chetopoda 
are to be found ; and if some species are more commonly to 
be met with in the open sea* as, for instance, the amphinomge, 
named by M. Savigny Pleione vagans , it appears that they 
may have been drawn along with marine plants by the cur- 
rents, as is the case with many other animals. 
A great many species are free and wandering* but others live 
in a tube without being fixed there. 
The position of this tube is rarely horizontal, and when it 
is vertical, should any chance displace it, the animal torments 
itself until it has recovered its proper station, as Pallas has 
frequently proved by experiments on the pectinariae. 
The locomotion of animals of this class is in general rather 
slow, and may be compared to that of slugs, to a certain ex- 
tent, though they have a great number of feet, or at least, as 
we have seen, of appendages that serve for locomotion. This 
is the case with the species which are most favoured in this 
respect, such as the nereides. In the aphroditus it is infinitely 
slower ; and is reduced to a nullity in the serpulae, the amphi- 
trites, and the sabellariae : in fact, they can only rise or sink in 
the tubes which they inhabit, by their fasciculi or hooked 
seta;. 
The nereides not only creep in a serpentine manner on the 
surface of solid bodies at the edge of the water, but they often 
swim very well, either by successive undulations of their 
bodies, like eels and serpents, or by even agitating their ap- 
pendages, which serve as oars. 
The chetopoda appear to be for the most part carnassial, and 
feed upon smaller animals than themselves which come within 
