FIRST CLASS OF ARTICULATED ANIMALS. 
THE ANNELIDA*, 
Are the only invertebratecl 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 previously 
joined it to the order of intestinal worms ; and Linnaeus, more anciently 
still, had placed a part of it among the mollusca, and another with the in- 
testinal worms. 
t It has been asserted, that the Aphroditas had not red blood. I think 
that I have observed the contrary in the Aphrodita Squamata. 
