ANNELIDES. 



91 



foe as weapons of defence, for which their slenderness and flexibihty 

 would render them of no avail. But we likewise find in the Aphro- 

 dites, and in several other genera, certain smooth tapered bristles 

 which are less numerous, not so flexible, nor so long, — sometimes 

 even short and stiff. These can be retracted within their own 

 sheaths entirely or in part ; and they may be used, like so many 

 needles, against any soft creature that offers umbrage or war. 



The simple bristles of some Annelides are clavate (fig. 16), of 

 which certain species of Lombrinera furnish examples. In the Pal- 

 myres there are bristles compressed upwards, and in some degree 

 spathulate (fig. 18). The dorsal branch of the foot of certain 

 Nereides, and more especially the ventral branch of that of Aphro- 

 dita aculeattty is furnished with bristles terminating in a sort of for- 

 ceps, or a fork with unequal prongs (fig. 4), either smooth or serrated 

 on the margins. In other Annelides, the bristles are channeled 

 towards their points (fig. 21), the sides of the groove being serru- 

 lated for a greater or less extent. We find bristles of this kind in 

 the Poly noes, which have the figure of a grooved j^ ^xy 

 probe ; others which are pointed like a lancet ; * * 



and in Polynoe scolopendrina, this lancet-like point 

 is bifurcated (fig. 15). There are other forms of 

 simple bristles which will be illustrated in the 

 descriptions of the species, — bristles imitative of 

 stilettos, pikes, scimitars, and saws, — and indeed 

 so various, that Man wonders, while he confesses 

 the fertility of Nature in her delicate inventions. 



The compound bristles are distinguished by being 

 composed of two pieces, the point distinctly articu- 

 lated to the shaft*. The shaft is the lower portion 

 (No. XIV. fig. 22 6), which is always imbedded in 

 the substance of the foot ; and it is on the end of 

 this portion that the joint is hollowed for the recep- 

 tion of the external portion or point (fig. 22 a). 



From the fineness of some of the compound 

 bristles, more especially of their points, it must be 

 evident that they cannot prove formidable weapons, 

 for a slight resistance will bend the outer portion, 

 and thrust aside the apex. There are, however, 

 others which are stronger and more rigid, and can 

 be made undoubtedly offensive. These are usually 

 a part of the armature of the ventral branch of 

 the foot. The shaft here supports a short point 

 fashioned like a hedge-bill or chopping-knife 

 (fig. 23) ; and it is probable that when the worm 

 has thrust this weapon into the enemy, or its prey, 

 it is loosened from its connexion with the shaft, and left to fester 

 in the wound. That this is the case with these, and some other 

 bristles of analogous conformation, we may conclude the more 



23 



* Not articulated, but welded to. See Williams, Rep. Brit. Assoc, p. 210. 



