98 SUPPLEMENT 



The appendages which furnish the sides of the rings of the 

 nereides are always much more complicated than in the true 

 lumbrici, and even than in the na'ides, but less so than in the 

 amphinomas, and neighbouring genera. They constitute, in 

 general, a small lamina, compressed from front to back, and 

 placed vertically on each side of the ring, of which it occupies 

 the entire upper part- But this lamina, or this species of fold, 

 is sometimes almost nothing, while at other times it is longer 

 than even the diameter of the ring, and forms a time pedicle. 

 This lamina, in its greatest state of complication, is divided by 

 an emargination, or a bifurcation, into two portions, more or 

 less distinct, placed one above the other. M. Savigny designates 

 them by the name of oars. The upper one is composed of a 

 soft, flexible, tentacular part, more or less elongated, some- 

 times giving out at its base a bifurcation, by way of branchial 

 appendage ; and of a fasciculus of hard, rigid, corneo-calcare- 

 ous setae, situated at the superior base of another tentaculary 

 nipple, which, after that, is constantly inferior. In the two 

 parts of the fasciculus of setae, there are almost alw^ays two 

 or three harder and stiffer setae, which M. Savigny names 

 acicidi. Sometimes, however, the setae are not divided. 



The simplification of this appendage may be considered to 

 commence by its non-bifurcation, but afterwards the denticu- 

 lations of the branchial lobe disappear ; then the branchial 

 lobe itself; the setae afterwards become attenuated by a dimi- 

 nution of their number, and are reduced in length. There re- 

 main then only the tentacular lobes. They subsequently 

 diminish, either both or one of them, and the appendage is 

 sometimes represented only by one or two small tubercles. 

 We may very well conceive too, that what are named eyes in 

 the nereides, are perhaps but the extremities of these rudi- 

 ments of tentacula. 



But this rudimentation (if we may use such a term) of 

 certain parts of the appendage in the nereides, is sometimes 



