TEREBELLA. 289 



side, and the whole may be removed entire, along 

 with the architect, which meanwhile has contracted 

 itself within the smallest possible space. 



The Terebella, when taken from its tube, is found 

 to be an Annelide 7 or 8 inches long, consisting of 

 numerous segments tapering towards the posterior 

 extremity (PL VI. fig. 1). Sixteen retractile pencils, 

 each consisting of fifteen or twenty bristles, border 

 the sides of the upper segments, but farther down 

 these degenerate into mere stumps. 



The anterior part of the body consists of a kind of 

 frill divided into three portions, surrounding the 

 roots of sixty, seventy, or a hundred tentacula, ac- 

 cording to the age or dimensions of the specimen, 

 with the mouth, which somewhat resembles a scoop, 

 in the midst of them. Immediately behind this frill, 

 three pairs of most beautiful scarlet tufts (the bran- 

 chiae) rise to the height of half an inch. 



The animal is universally of a peach-blossom 

 colour, with a broad, taper, smooth, bright carmine 

 stripe descending along the belly. 



If a specimen be dislodged from its tube, it swims 

 by violent contortions in the water, after the manner 



v 



of various other marine Annelidans; the tentacula 

 and the branchiae are compressed and contracted 

 about the head like a brush, and, as the animal be- 

 comes very soon exhausted by such unnatural exer- 

 tions, it soon sinks to the bottom. Should a quan- 

 tity of sand be now scattered from above, the ten- 

 tacula, speedily relaxing, extend themselves in all 

 directions to gather it up, sweeping the vessel quite 

 clean ; so that in a very short time not a particle is 



o 



