and of the base or cupule (6). When the spine is forcibly torn away from its sheath, the cupule is detached, and remains adherent to the fascicle of muscular fibres in which it is implanted. The Bristles are much varied. They may be divided in the first place into the simple and compound*. The simple bristles (No. XIII. fig. 12-21) are formed of a single piece only; or if any are composed of several pieces, these are all of the same kind, and superadded to one another like the articulations of the filiform or setaceous antennæ of certain insects, or rather like the joints of a Conferva (fig. 12). The form of the simple bristle is very variable. Some terminate in a more or less sharp point, either cutting, denticulated, or forked (figs. 13, 14); others are obtuse and rounded, or even enlarged at the extremity (figs. 15, 16). Some are of such extreme fineness, that they may more properly be called hairs than bristles (fig. 17). Such are the beautifully coloured metallic and iridescent hairs which garnish the sides and feet of the Aphrodites; and in some species of this genus a portion of these long hairs is interlaced so as to form a sort of felted membrane to cover the scales and branchia, and protect them from injury. But the utility of such hairs, in other respects, is of a passive kind :-they may make the worm troublesome to the palate of a foe, but they cannot be directed against that *The figures of Oersted in pl. 1 of his Annul. Dan. Consp.' are excellent. foe as weapons of defence, for which their slenderness and flexibility would render them of no avail. But we likewise find in the Aphrodites, 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 Palmyres 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 Aphrodita aculeata, is furnished with bristles terminating in a sort of forceps, 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 serrulated for a greater or less extent. We find bristles of this kind in the Polynoës, which have the figure of a grooved probe; others which are pointed like a lancet ; and in Polynoë 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 articulated 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 reception of the external portion or point (fig. 22 a). No. XIV. α 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 22 * Not articulated, but welded to. See Williams, Rep. Brit. Assoc. p. 210. certainly because of their exact resemblance, in miniature, to the different forms which the ingenuity of man has given to his instruments of warfare to render them more hurtful and deadly; and man possesses none which are better adapted to their purpose than the bristles with which certain Annelides are furnished. In fact, we can find no fitter instruments wherewith to compare the annelidan armoury, than harpoons, bayonets, lances, spears, and billhooks*. The harpoon-bristle offers this peculiarity,—it is not always complete, and it appears to be produced sometimes only when No. XV. required. If we figure to ourselves a very acutely pointed bristle marked obliquely by a cross line beneath, indicating the place of junction between the point and the shaft, we shall have a pretty exact idea of the reality (No. XV. fig. 24). The use of this novel weapon seems to be sufficiently indicated by its shape. It is evident that if the bristle is thrust deep enough into an opposing body so that the harpoon is wholly immersed, this cannot be again withdrawn on account of the hold taken by the reverted tooth. And as this connexion might prove inconvenient, if not dangerous, to the worm, when the enemy was equal in bulk, or more powerful than itself, it has the power of detaching the harpoon from the shaft, and keeping itself thus at freedom to act, and to renew the battle. Audouin and M.-Edwards have noticed several individuals that, from being apparently engaged in repeated combats, had lost all these weapons. Yet, though they were thus deprived of an essential part, the bristles were still formidable enough; for as the harpoon breaks off at the joint in an oblique manner, the shaft is left with an acute sloped apex, against which no soft creature could press without danger of a severe wound. 24 The structure of the bayonet-bristles (No. XVI.fig.25-27) is more complicated. These are armed with a kind of pricker which is joined on to the extremity and side of the shaft in much the same way as a bayonet is fixed to the end of a musket (fig. 25). This appendage is not only very sharp, and formed with several cutting surfaces, but it is incised below into a spine pointed backwards (a), which gives it the advantage and property of a harpoon. Hence, having been forced to penetrate the flesh, the point cannot be again extricated, but is detached at once from the side of the shaft on which it was articulated. This, however, is not the most curious part of the instrument; and were it *The Bristles: fixed resemblances "to implements of ordinary use," but so small in size, and so delicate in tooling, that they are made rather for the admiration of man than for the use of the worm that bears, &c. The Satan of the ancient "Mysteries" was "a werm with an aungelys face." "Ils offrent cela de remarquable, que le harpon ne se montre pas toujours tout formé, et qu'il paraît quelquefois ne se produire que lorsque le besoin l'exige." -Ann. des Sc. Nat. xxvii. p. 378. No. XVI. desirable to have any addition to man's weapons fit for war, it might furnish the model of a new kind as formidable as any we yet possess. The bayonet part of the bristle is, in fact, also a sheath, which encloses another weapon that is only exposed when the scabbard has been lost. When we separate the bayonet from the shaft, we, at the same time, force from its interior a horny stylette (fig. 26 6),-the true termination of the bristle, so that the place where the bayonet is attached is not obtuse or inflated, as it seems to be, but is, on the contrary, tipped with a needlelike point, ready to become a good defensive instrument when the enclosing appendage has been lost or expended. The Aphrodita hystrix has, in the dorsal branch of its feet, bristles of a very different composition, and which may be described as lances*. It is easy enough to form a notion of their form by recalling to ourselves the figure of a lance, or of a long pike barbed on the edges near the apex (No. XVII. fig. 28); and let it be remembered that the lances of the Annelid are so small that a considerable magnifier is required to discover their workmanship, which excels in finish the finest instrument manufactured by the skill and patience of the most expert artificer; for, unlike man's productions, 25 26 27 this tiny lance "not only bears the microscopic glance, but the more minutely it is examined, the more fully its exquisite organization is disclosed t." A great number of these bristles garnish the extremity of each foot, and as they are stiff and serried, they form a hedge of spears round the body of the worm, placing it, as it were, within a square of pointed pikes threatening at all points. Associated with the lance-bristles, there are found, in the same Aphrodite, numerous others terminating in a sort of knob (fig. 29). When this knob is opened longitudinally, there is found within it a barbed lance, in all respects resembling those just described (fig. 30). So the lance-bristles appear to be bristles which have been deprived of their sheaths. The sheath secures only the barbed point, and each barbule has its own little separate sheath or furrow, as may be seen on separating the valves of the main sheath. Then, on inspection of the inner side of either valve, it is not difficult to discover * "Flèches" is the term used by Audouin and Milne-Edwards; but as the weapon is thrust, and not shot, I have preferred lances to arrows. + See the Chapter LI.-" Art and Nature compared,"-in 'Baker's Microscope made easy,' p. 292, 3rd edit. Lond. 1744. In reference to Aphrodita hystrix, Mr. Alder writes me: "They are very inconvenient neighbours in a bottle, as their sharp spines stick into everything; and in examining the contents of a dredge where they are, they pierce the fingers, breaking in and becoming very painful."-Letter, Feb. 17, 1854. the little gutters in which the barbules are laid, and which are accurately adapted for their reception. The end of this singularly beautiful and complicated apparatus is obvious enough. Like the bristles of the Annelidans in general, the lance-bristle is retractile; but as the barbules are pointed backwards, it could not have been drawn within the soft body without a painful laceration of the parts. To obviate this, a sheath has been provided to enclose the whole; and thus covered, the bristle moves with an easy play. Nor is it difficult to explain how, when the barbed point is needed by the necessities of the worm, the sheath is put aside. This consists of two pieces or valves accurately adapted to each other, leaving a small fissure or gape where they meet above, and through which the apex of the lance is occasionally seen protruded. The sheath is also flexible and elastic, and its valves, which are naturally in close opposition, are capable of easy separation. Thus, when an enemy or prey comes in contact with the apex of the lance, this is thrust through the gape of the valves onwards to penetrate the opposing object; and by the protrusion, the sheath, having lost the support it had from the lance, is not only separated into its valves, but these are bent and folded backwards. They return again to their natural position and closure as the lance is withdrawn, and this is effected by their inherent elasticity*. Other forms of Bristles will be described as they occur to us in our examination of the species. In the meantime, as we are dealing in marvels, let me ask the naturalist to count the number which may be required to furnish the garniture of a single individual. There are Annelides which have 500 feet on each side,-each foot has two branches, and each branch has at least one spine and one brush of "In human works, though labour'd on with pain, Yet serves to second too some other use.' POPE, Essay on Man, Epist. i. 1. 53. |