WORMS. 



226 



Order II. — POLYCH^TA. 



The members of this order are generally dioecious, Jind pass through striking 

 metamorphoses in the course of tlieir development. The head is conspicuous on 

 account of the feelers, cirri, and 

 gills, which are often very promi- 

 nent. They are nearly all ma- 

 rine. They far exceed all other 

 worms in the variety of species 

 and the diversity of theii- lives : 

 indeed within our limits it is 

 utterly impossible to refer even 

 to all the families of the Poly- 

 chseta, unless we should content 

 ourselves with a bare catalogue. 

 Roughly speaking, a polychsetous 

 annelid may be recognized by its 

 jointed body, the false feet with 

 numerous bristles, and the pos- 

 session of cephalic tentacles. The order has two main divisions 

 Tubicolae; 2, Errantia, 



Fig. 216. — Head and anterior segments of Diopatra cuprea. 



1, Sedentaria or 

 the former with fifteen, the latter with twelve families. 



Sub-Order I. — Txibicolje. 



This sub-order owes its name to the general habit of building a tube in which th^ 

 worm lives. The dwelling is con- 

 structed, now of one kind, now of , 

 another, of foreign particles, accord- 

 ing to the tastes and habits of the 

 builder, who cements his materials 

 together by a secretion of his own 

 body, or sometimes the secretion 

 itself hardens, making a tube with- 

 out extraneous adjuncts. From the 

 fact that their lives are spent in 

 this armor, the anterior end of the 

 body becomes highly specialized, 

 and is usually very different from 

 the more posterior segments. 



The handsome Terebella (Am- 

 phitrite) ornata of our North At- 

 lantic coast, a large and interesting 

 Fig. 21T. — cistenides worm, is common both among and 



qauldii^ a tube- ^ , - ^ ^ , 



worm removed under rocks, and on muddy shores. , . . 



from its tube. ^ , n j. -\, 4. j! it, YlQ..2li. — Am.phttr%te ornata. 



It constructs firm tubes out ot the 

 consolidated mud and sand in which it resides, casting cylinders of mud out of the 

 orifice. It grows to be twelve or fifteen inches in length, and is usually flesh-colored, 

 vol.. I. — 15 



