SCALE -WOEM. 163 



animal was in my possession, one and another of these 

 appendages was cast off at almost every time that I 

 roused it to action ; and even when allowed to remain 

 quiet, the denuding process went on, so that in a few 

 days it was nearly half naked. This process of self- 

 mutilation will sometimes go on till scarcely a single 

 shield remains out of the double series. 



This dull-coloured Scale-worm presents peculiarities 

 of structure which are eminently worthy of careful 

 examination. The body, like that of the other species 

 we have just been considering, is composed of many 

 rings or segments, each of which bears on its upper 

 surface a little wart or tubercle on each side, to the 

 summit of which is slightly attached the circular leaf- 

 like shield just described. Beneath the shadow of this 

 broad shield the segment projects laterally into another 

 tubercle, whence issue the organs of motion, which in 

 these Annelids are of highly curious structure. In 

 this species they consist of a bundle of straight bristles 

 of exquisite tenuity, and having a silky lustre; they 

 are of unequal length, the upper ones being the longest, 

 and the pencil diminishing pretty regularly downwards. 

 The microscope shows them to be about one hundred 

 in number in each bundle ; and each bristle to be a 

 delicate oar consisting of a slender stem, apparently 

 tubular, dilated at the tip into a narrow blade terminat- 





