Page:The aquarium - an unveiling of the wonders of the deep sea.djvu/306

Rh side of which is attached by a short footstalk the beautiful pall-like leaflet, and on the under side a similar smaller one, the tip of the foot projecting between them. This point is perforated to give emission to the pencil of bristle-spears, which are arranged like a fan, and are, at the will of the animal, projected to a considerable length from the foot, or withdrawn completely into its interior, as into a sheath. Each individual bristle is composed of a very slender, long, straight shaft, terminating in a knob somewhat resembling the end of a limb-bone. This is slit in one direction to receive the terminal lance-head, which is fitted into it exactly as a knife-blade is fixed into its handle. It is in fact a knife-blade having a thickened back, and a very thin edge, which is notched with teeth of the most delicate subtilty. The blade is slightly curved, and drawn out to a long acute point; and the whole space is formed out of a substance that rivals the purest glass.

The full use of these most exquisitely contrived and finished organs is, I think, yet to be discovered. They are doubtless instruments of locomotion, being evidently used to push the animal along, as a ferry-man propels a boat with his pole; and the saw-like teeth may serve to catch the roughnesses of the surfaces along which it is moving. It is possible also that they may be weapons of defence; for, being thrust out at every laternal undulation of the segments, they present formidable chevaux de frise to any small enemy who may entertain malice prepense againtagainst [sic] the Annelid. Still the situation of these arms is hardly such as we should expect, if this were their primary