ON ANNELIDA. 
Ill 
The arrangement of the species of nereides, according to M. 
de Blainville, should indicate the passage from the aphrodites, 
which he places at the commencement of the class ofChetopods, 
to the lumbrici, which are at the end. It should be establish- 
ed on the development of the appendages in general, and parti- 
cularly on those of the head. More regard, however, has been 
paid by naturalists to the mode in which the mouth is armed. 
The genus Eunice of the text is put at the head of the 
Nereides by M. de Blainville ; the anterior extremity of the 
digestive canal is provided with a buccal mass, armed at the 
interior with corneous folds or teeth, denticulated, and lateral, 
the two inferior of which are very much approximating the 
medial line, and constitute a sort of lower jaw. 
This group encloses the largest species of nereides ; many 
appear to exist in the European seas, but they are never of so 
large a size as those of the seas of warm climates. 
The corneous or calcareous armour which invests the lateral 
folds of the buccal cavity in these nereides, would lead us to 
suppose that their food was more solid than that of the others, 
and that they might even attack the smaller fish. 
We shall conclude our remarks on the present order of 
annelida with a brief notice of the aphrodites. 
This is a genus of marine worms, the character of which 
is to have membranaceous plates in the form of a scale, 
which form two ranges on the back, where they are attached 
by their middle, one pair fastened to two of the rings. The 
gills are placed on those rings which have no scales, and so 
small that they can hardly be perceived; each ring, more- 
over, supports feet composed of stiff setae, which vary in num- 
ber according to the species. 
The body of the aphrodites is generally broader and flatter 
in proportion to its length, than that of other worms of the 
same family. It has been supposed that they have articulated 
tentacula round the mouth, but this is erroneous ; they are 
