262 



ANNELIDA. 



Fig. 129. 



fragment. This half of the divided worm, like the former, gradually 

 presents evidences of decay: it becomes less and less irritable, the 

 muscles and integuments begin to decompose, the blood-vessels of the 

 branchi become black, and the whole disappears by the dissolution of 

 the structures. 



(674.) The APHRODITACE^:, or Sea-mice, are remarkable for the long 

 hairy tufts with which their pedal appendages are generally furnished 

 (lig. 129). Nothing can exceed the splendour of the colours that orna- 

 ment some of these fasciculi of hairs ; they yield, indeed, in no respect 

 to the most gorgeous tints of 

 tropical birds, or to the bril- 

 liant decorations of insects: 

 green, yellow, and orange 

 blue, purple, and scarlet all 

 the hues of Iris play upon them 

 with the changing light, and 

 shine with a metallic efful- 

 gence only comparable to that 

 which adorns the breast of 

 the humming-bird. But it is 

 not for their dazzling beauty 

 merely that these seta3 are re- 

 markable ; they are not un- 

 frequently important weapons 

 of defence, and exhibit a com- 

 plexity of structure far be- 

 yond anything to be met with 

 in the hair of higher animals. 

 In the Aphrodite aculeata, for 

 example (fig. 129, A), they are 

 perfect harpoons ; the point 

 of each being provided with a 

 double series of strong barbs 

 (fig. 129, B) ; so that when the creature erects its bristles much more 

 formidable than those of the Porcupine the most determined enemy 

 would scarcely venture to attack it. 



(675.) But here we cannot help observing an additional provision, 

 rendered necessary by the construction of these lance-like spines. We 

 have before noticed that the bundles of setae are all retractile, and can 

 be drawn into the body by the muscular tube from whence they spring. 

 It would be superfluous to point out to the reader the danger which 

 would accrue to the animal itself by the presence of such instruments 

 imbedded in its own flesh, as by every movement of the body they would 

 be inextricably forced into the surrounding tissues. The contrivance 

 to obviate such an accident is as beautiful as it is simple. Every barbed 



Aphrodite aculeata. 



