108 
SUPPLEMENT 
dwelling-place, such as holes or anfractuosities, which they 
inhabit. 
The organs of generation are still more obscure. It ap- 
pears, however, that we may consider as ovaries some small 
whitish utricles, granular, which are found on each side of 
each ring, and between the cceca of the stomach, the orifice 
of which appears to exist at the base of its appendage, so 
that these animals should have a large number of ovaries. 
They do not, however, possess their full development but in 
the extent of about three-fifths of their total length. In front 
they are very small, and still more so behind. 
The nervous system consists in a long abdominal and 
medial thread, extended from one extremity to the other, 
and often concealed by fasciculi of the inferior longitudinal 
muscle. In certain species it does not merely form a thread, 
but it swells a little in the middle of each ring, and it is from 
this enlargement that the threads come forth which go to the 
muscles and the skin. In the nereis pelagica we find even 
that these ganglions, about the second anterior third of the 
body, are very thick and very distinct, while they are so little 
so elsewhere, as to lead us to doubt of their nature. 
No naturalist has yet studied the different functions of the 
organs which constitute the nereides. The faculty, however, 
of continuing to live, has been recognized in them, after a 
considerable portion of the posterior extremity of their bodies 
has been cut off, the amputated part being reproduced in a 
tolerably short time. 
Their eyes appear to be but of very small utility to them ; 
but it is not so with the tentacular cirri of their body, and 
especially with those of the head, which they direct in all 
ways, as it were to examine and scrutinize those obstacles 
which may occur to them. 
Their locomotion on a resisting soil is very lively, and is 
