FIRST CLASS OF ARTICULATED ANIMALS. 



THE ANNELIDA*, 



Are the only invertebrated animals with, red blood ; it circu- 

 lates in a double system of complicated vessels f. 



Their nervous system consists in a double knotted cord, like 

 that of the insects. 



Their body is soft, more or less elongated, and often formed 

 into a very considerable number of segments, or at least of 

 transverse folds. 



Almost all of them live in the water (the earth-worms or 

 lumbrici excepted) ; many bury themselves in holes in the 

 bottom, or form tubes there with the ooze, or other sub- 

 stances, or even exude a calcareous matter, which produces a 

 sort of tubular shell. 



* I established this class, distinguishing it by the colour of its blood 

 and by other attributes, in a memoir read at the Institute in 1802. See 

 Bullet, des Sc. Messidor. An. X. where I have principally described the 

 organs of circulation. M. Lamarck adopted, and named it Annelida, in 

 the extract from his course of Zoology, 1812. Bruguieres had pre\'iously 

 joined it to the order of intestinal worms ; and Linnaeus, more anciently 

 still, had placed a pai't of it among the mollusca, and another with the in- 

 testinal worms. 



t It has been asserted, that the Aphroditce had not red blood. I think 

 that I have obsei-ved the contrary in the ApTirodita Squamata. 



