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 atthe commencement of the class of Chetopods, 

 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 vs^orms, 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 



