. ANNELIDES. 447 



The branchiae of some resemble tufts or arbusculsBj attached 

 to the head or anterior part of the body : they, nearly all, 

 inhabit tubes. We will call them the Tubicol^. 



Those of others resemble trees, tufts, laminae or tubercles 

 in which vessels ramify, and are placed on the middle of the 

 body : most of them inhabit mud or swim in the ocean, the 

 smaller portion being furnished with tubes. We name them 



the DORSIBRANCHIAT^. 



Others again have no apparent branchiae, and respire, either 

 by the surface of the skin, or as some authors opine, by the 

 internal cavities. Most of them live free in mud or water ; 

 some of them only, in humid earth. They are the Abran- 

 chiate. 



The genera of the first two orders are all furnished with 

 stiff setae, of a metallic colour, that issue from their sides, 

 sometimes simply, and at others in fasciculi, which serve in lieu 

 of feet ; but there are some genera in the third order which 

 are deprived of that support(l). 



The special attention paid by M. Savigny to these feet or 

 organs of locomotion, has resulted in the distinction of the 

 following parts : 1 . The foot itself, or the tubercle which sup- 

 ports the setae ; sometimes there is but one to each ring, and 

 at others there are two, one above the other, styled a simple 

 or double oar. 2. The setae, which compose a fasciculus for 

 each oar, and which vary greatly in form and consistence, 

 sometimes constituting true spines, and at others fine and flex- 

 ible hairs, frequently den tated, barbed, &c.(2) 3. The cirri 

 or fleshy filaments adhering to the foot, either above or be- 

 neath. 



The head of the Annelides of the two first orders is gene- 



(1) M. Savigny has proposed a division of the Annelides, to be founded on the 

 presence or absence of these locomotory set:e; those in which they are wanting 

 being reduced to Leeches. M. de Blainville, who has adopted this idea, forms 

 his class of the Entomozoari.t: Chetopodes with tlie Annelides with setae, and 

 that of the EntomozoarijTs Apodes with those which liave none, but in mixing 

 many of the Intestini with the Apodes, he has done -what M. S. did not do. 



(2) See on this subject the Mem. of M. Savigny on the invertebrate animals, 

 and those of Messrs Audouin and M. Edwards on the Annelides. 



