446 ARTICULATA. 



CLASS I. 



ANNELIDES(l). 



• 



The Annelides are the only invertebrate animals that have 

 red blood. It circulated in a double system of complicated 

 vessels(2). 



Their nervous system consists in a double knotted cord, 

 like that of insects. 



Their body is soft, more or less elongated, and divided into 

 a, frequently, considerable number of segments, or at least of 

 transverse plicae. 



They nearly all inhabit the water — the Lumbrici or Earth- 

 worms excepted; several penetrate into holes at the bottom, 

 or construct tubes there with the ooze or other matters, or 

 even exude a calcareous substance, which envelopes them with 

 a sort of tubular shell. 



Division of the Annelides into three Orders. 



This class, which contains but few species, presents a suffi- 

 cient basis of division in its organs of respiration. 



(1)1 established this class, distinguishing it by the colour of its blood and other 

 attributes, in a Memoir read before the Institute in 1802. See Bullet, des Sc, 

 Mesidor, an X, where I described the organs of the circulation. 



M. Lamarck has adopted and named it Annelides. Brugieres previously united 

 it to the order of the intestinal worms, and before him, Linnaeus placed part of 

 these animals among the Mollusca, and the rest among the Intestlni. 



(2) It has been asserted that the blood of the Aphrodit?e is not red. I think I 

 have observed the contrary in the .Iphrodita squamata. 



