ZOOLOGY 



The Poly- 

 chaete or 

 many- 

 bristled 

 worms 



arthropods. Then there are the bristles, often placed 

 (as in the marine Nereis) on lobelike outgrowths which 

 resemble rudimentary legs. The head, though without 

 antennae', may be provided with long tentacles, and we 

 can often recognize jaws which are very like those of 

 an insect. Thus we have an animal which satisfies in a 

 general way the requirements of an ancestor of the ar- 

 thropods, foreshadowing their characters, though not of 

 them. The comparatively low organization is shown by 

 the fact that many marine worms retain the method of re- 

 production by constriction or budding, forming a series of 

 individuals joined at the ends, like a string of sausages, 

 ultimately coming apart. This goes with true sexual 

 reproduction, as we have found in the lower groups. 



3. Polychaete worms 

 are aquatic, and al- 

 though a few species 

 live in fresh water, the 

 sea is the habitat of 

 the vast majority of 

 the species. Some are 

 free swimming, others 

 make tubes, often re- 

 minding us of those 

 constructed by insect 

 larvae. Many are beau- 

 tifully colored, and this 

 ornamentation may be 

 due to different causes. 

 Sometimes the bristles 

 densely covering part 

 of the body are splen- 

 didlv iridescent. In From Perrier ' s " Trait * de Zoologie " 



FIG. 60. A Polychaete worm, Amphilnte 

 Other Cases the red, edwardsii; about f natural size. 



