CLASS ANNELIDA. 



Division of the Annelida into Tfiree Orders. 



This not very numerous class, presents in its respiratory 

 organs, the bases of satisfactory divisions. 



Some have gills in the form of plumes, or arbusculae, at- 

 tached to the head, or to the anterior part of the body. Almost 

 all of them inhabit tubes. These we call Tubicol^. 



Others have on the middle part of the body, or along the 

 sides, gills in the form of trees, tufts, laminae, or tubercles, in 

 which the vessels ramify. Most of them live in the mud or 

 ooze, or swim in the sea. The smaller number have tubes. 

 We name them Dorsibranchia. 



Others, in fine, have no apparent gills, and respire, either 

 by the surface of the skin, or as some believe, through internal 

 cavities. Most of them live freely in water or mud ; some 

 only in humid earth. We call them Abranchia. 



The genera of the first two orders have all stiff hairs, or 

 bristles, and of a metallic colour, issuing from their sides, 

 sometimes simple, sometimes in bundles, and supplying the 

 place of feet. But in the third order there are some genera 

 destitute of such support *. 



The special study which M. Savigny has devoted to those 

 feet, or organs of locomotion, has caused him to distinguish, 

 1. The foot itself, or the tubercle which supports the bristles: 

 sometimes there is but one to each ring ; sometimes there are 

 two, one above the other ; this is what is named simple or 

 double oar. 2. The bristles which compose a bundle for 



* M. Savigny has proposed a di\'ision of Annelida, according to their 

 having bristles for locomotion or not; these last being reduced to the 

 leeches. M. de BlainviUe, who has adopted this idea, makes of the An- 

 nelida which have bristles his class of Entomozoa chetopoda, and of those 

 which have none, that of Entomozoa apodaj but (what M. Savigny did 

 not do) he intermingles, among the apoda, several of the intestinal worms. 



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