TUBE-WORMS, 



frequeni.lv dredged up from muddy ground. The Annelid is four or five inches in length 

 of a greyish hue, and clothed on the back with a fine silky down, under which are 

 concealed fifteen pairs of scaly plates, one pair on each ring. The under surface is 

 smooth, but marked by transverse divisions, indicating that it is formed of about forty 

 rings or segments. On the sides project bunches of hairs resembling the finest silk, and 

 bedizened with iridescent colours ; they yield, indeed, in no respect to the most gorgeous 

 tints of tropical birds, or the brilliant decorations of insects : green, yellow, and orange, 

 blue, purple, and scarlet, all the hues of the rainbow play upon them with the chang- 

 ing light, and shine with a metallic effulgence only comparable to that which adorns 

 the breast of the humming-bird. But it 

 is not only for their dazzling beauty that 

 these worms are remarkable : many of 

 them are armed with spines, that con- 

 stitute important weapons of defence ; 

 each of these spines is seen, under the 

 microscope, to be a perfect harpoon, its 

 point being provided with a double series 

 of strong barbs, so that when the crea- 

 ture erects its bristles, much more for- 

 midable than the spines of a hedge- 

 hog, the most determined enemy. would 

 scarcely venture to attack it. The^e 

 spines are all retractile, and can be 

 drawn into the body by the muscular 

 tube from which they spring. It would 

 be superfluous to point out the danger that would accrue to the animal itself by the pre- 

 sence of such instruments embedded in its body, as by every movement they would be 

 forced into its own flesh. The contrivance to obviate such an accident is as beautiful as 

 it is simple : every barbed spine is furnished with a smooth, horny sheath, composed 

 of two blades, between which it is lodged (Fig. 64), and these, closing upon the barbs 

 when they are drawn inwards, effectually protect the neighbouring soft parts from 

 laceration. 



FIG. 64. SEA-MOUSE. 



FIG. 65. SEKPI.-LA. 



THIRD ORDER TUEICOLOUS AXXELIDAXS. 



The Tubicolous Annelidans, as their name imports, reside in 

 tubes, which are either composed of a dense shelly substance, or 

 constructed by gluing together fragments of sand, small stones, 

 and other similar materials. To the former section belong 



