nOILMS. 



OitDEii II. — I'OLYCH.ETA. 



The members of this order are generally dioecious, and pass throuoh strikino- 

 metamorj)hoses in the course of their 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 their lives : 

 indeed within our limits it is 

 utterly impossible to refer even 

 to all the families of the Poly- 

 chwta, unless we should content 

 ourselves with a bare catalogue. 

 Roughly speaking, a ])olychR'tous 

 annelid may be recognized by its 

 jointed body, the false feet with 

 numerous bristles, and the pos- 

 session of cejihalic tentacles. The order has two main divisions: 1, Scdcntaria or 

 Tubicolse; 2, Errantia, — the former with fifteen, the latter with twelve families. 



i ^VU 





Fig. 21(5. — Head ,iinl anterior segments of JJinjmtm riipr. 



Sub-Oeder I. — TvincohJE. 



rder owes its name to tlie general habit of bui 

 worm lives. The dwelling is con- 

 structed, now of one kind, now of 

 anothei', of foreign particles, accord- 

 ing to the tastes and habits of the 

 builder, who cements his materials 

 together by a secretion of his own 

 bod)', or sometimes the secretion 

 itself hardens, making a tube with- 

 out extraneous adjuncts. From the 

 fact that their lives aie S])ent in 

 this armor, the anterior end of the 

 body becomes highly specialized, 

 and is usually very different from 

 the moi-e posterior segments. 



The handsome TereheUa {Am- 

 phitrite) ornata of our North At- 

 lantic coast, a large and interesting 

 worm, is common both among and 



a tube in which the 



Fio. 217. — Ciafmiffes 



rinnhUi, a tube- i i , 



worm removed under rocKS, and on muddy shores. 



from its tube. r. i ' i. , 



It constructs nrm tubes out or the 



Fig. 218. — Amphilrite 



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 



