The progress of all species of bêche-de-mer is sedate and cautious, and this, probably the longest and the weakest and limpest of all, surpasses the race in deliberateness. It cannot move as a whole, so it progresses in sections. When the head has been advanced to its utmost, about the middle of the body an independent series of succeedant ripples or wrinkles manifests itself and travels consistently ahead, while farther towards the rear another series follows, and so on, until the lagging tail is enabled to wrinkle itself along. But the animal is endowed with the capacity of quite suddenly retracting its forepart like the bellows of a concertina, and when so compressed to heave it backward or in any direction, so that an immediate change of route is possible. The retraction and uplifting of the foreshortened part is astonishingly rapid in view of the methodic movements of the animal as a whole. It is also notable that when the retraction takes place the tentacles are entirely withdrawn, otherwise they are for ever anxiously exploring every inch of the toilsome way. Scientific men have entitled one of the species--possibly the very one blunderingly introduced--SYNAPTA BESELLII, and brief reference is made to it elsewhere. One member of the great "sea-cucumber," or BÊCHE-DE-MER, family is especially noticeable because it is decorated with colours of which a gaily plumaged bird might be envious, though it has no other claim to comeliness. Most primitive in form--merely a flattened sac, oval and four inches long by three inches broad, with a purple and white mouth puckered as if contracted by a drawn string. Its general tint is grey; longitudinal bands of scarlet, green, violet, and purple radiate from the posterior and converge at the mouth, the hues blending rainbow-like. The brighter colours seem to have been carelessly and profusely applied, for they run when touched and smear the fingers. Among a family generally sad-hued and shrinking so conspicuous an example is quite prodigal and invites one to ponder upon the sportfulness of Nature. What special office in her processes does this fop of the species with prismatic complexion perform? The functions of bêche-de-mer are not only interesting, but requisite in the commonwealth of the coral reef, however purposeless to the observer intent upon the obvious and external only; while the genera are so numerous that doubtless to each species is consigned the performance of a special office. Some seem to delight in a diet of slush of the consistency of thin gruel; others prefer fine grit; others, again, coarse particles of shell and coral grit and rough gravel. Peradventure the actual food consists of the micro-organisms in the slush and on the superficies of the unassimilatable solids.