130 LECTURE XI. 



energies in a linf^ai" direction, and forms successive segments from 

 before backwards. We find, in fact, at the lowest step of the great 

 Homogangliate series of the Animal Kingdom an extensive group of 

 vermiform animals, some of which very closely resemble the Trema- 

 tode, and others the Nematoid, Entozoa, and all are devoid of jointed 

 limbs : but they possess a distinct circulating system of arteries and 

 veins, and in almost all the species the blood is red. They have 

 therefore been called " red-blooded worms," " vers a sang rouge," 

 and " anellides," by the French naturalists ; in Latin A?iellata, from 

 anellus, a little ring, because the entire body of these worms is made 

 up of a succession of segments like little rings. 



The mind is not easily liberated from the sway of opinions that 

 have long been held as authoritative ; although Cuvier seems to have 

 been the first to detect the exaggerated importance of the zoological 

 character derived by Aristotle from the colour of the blood, yet the 

 judgment of the great modern reformer of zoology continued to be 

 so far biassed by that character, that in his latest edition of the 

 ** Regne Animal," he continued to place the Anellides, on account of 

 the colour of their circulating fluid, at the head of the articulate 

 series, above the Crustaceans, above the Arachnidans, above the 

 Insects, whose transitory larval condition these apodal worms seem 

 permanently to represent. 



The body of an Anellide is always very long, soft, and subdivided 

 into a number of segments, for the most part closely resembling or 

 identical with each other. In many species the first segment is so 

 slightly modified as scarcely to deserve the name of head ; in others 

 it is the seat of higher senses and more varied functions, and is at 

 once recognisable as the cephalic segment. 



In the lowest forms of the Anellata the locomotive instruments 

 are suctorial discs, as in the Trematode worms ; but the suckers 

 are always two in number, and are terminal in position. The species 



next in order have stiff hairs or mi- 

 nute hooks projecting from each seg- 

 ment. In most Anellides there is on 

 each side of the body a long row of 

 tufts of bristles, supported upon fleshy 

 tubercles, which indicate the rudi- 

 ments of lateral and symmetrical lo- 

 comotive members, (^fig- 68.) There 

 are often two such organs, placed one 

 («) above the other (^), on each side 

 Aphrodita. of the Segments of the body. In some 



species the two setigerous tubercles 



