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 coeca 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 verj^ lively, and is 



