A secondary pencil of bristles also issues from the upper side of each of these tubercular sheaths, so as to project diagonally upwards and outwards beneath the edge of the shield-leaf. This pencil consists of between thirty and forty bristles, which are connected with a cartilaginous rod exactly similar to that of the primary bundle. These bristles run off to a very fine point, and each one is marked on both sides with serratures so delicate as to be only just discernible with a magnifying power of 300 diameters. There are thus about 270 movable bristles of exquisite structure in each segment, which multiplied by 36, the number of segments in the body, gives a total of 9720 distinct organs of motion possessed by this animal, besides the broad leaf-like shields, which perhaps may act as fins, and the short tentacular feet, one of which is placed beneath the primary bristle-sheath, on each side of the segment.
By dissection after death, I have found the proboscis in the form of a long oval sac, very muscular and firm, of a blackish hue, lying in the anterior part of the body, which, on being cut open, showed four horny teeth placed in its neck so as to meet each other in the centre. I have never seen the protrusion of this organ during life, but if it is capable of being wholly everted, as in many species, these teeth must be turned on the outside, where they would seem to be of little use. Possibly, however, the version may be only just sufficient to bring these teeth to the margin, when their action might be made very efficient by the slightest alteration in the contraction of the sac.
Some species of this genus construct for themselves enveloping tubular cases, out of mucus given off from their bodies, and fragments of shells. In these they ordinarily live concealed, but are sufficiently active when they leave their houses. Some shine with a phosphorescent radiance in the dark.
In the great class of Worms, special organs for locomotion are often altogether lacking; and, where found, are only rudimentary. Alternate swellings and contractions of certain portions of the body are a great source of progression; and these are effected by the fluids of the interior, which are driven to a given part of the cavity, and momentarily imprisoned there by the contraction of the circular tegumentary muscles before and behind it; the body swelling at that place. “The muscles of the integument are then excited to action, and the fluid is forcibly compressed forwards or backwards, according to the direction of the muscular agency. Nearly all Annelids are struck with paralysis when this fluid is made to escape from its cavity by a puncture through its external walls. The power of voluntary motion is suspended; the body of the worm becomes passive and flaccid.”[85]
GOODNESS OF GOD.
These details convey but a feeble and imperfect notion of the numerous and elaborate contrivances which are so profusely bestowed upon these mean and grovelling worms; but they show how careful is the Creator of their well-being; how lavish of His mercies towards His meanest creatures. How unreasonable, then, is it for those to doubt His ever-watchful and unerring tenderness towards themselves, who have been made the objects of His redeeming love, and who, on the ground of redemption, “are of more value” in His sight, than all these His lower creatures put together!
VII.
JULY.
TWO-SPOTTED SUCKER.
A mile or two eastward of Babbicombe and Petit Tor, in from ten to fifteen fathoms water, there lies a stretch of flat stony bottom, reaching away from the island known as the Ore Stone, towards the mouth of the river Exe. This is a bit of ground to which a boatman whom I occasionally employ often resorts with the dredge, and rarely or never without a fair harvest of curious and interesting creatures. Among other things he brings me from time to time numerous specimens of what Yarrell calls the Bimaculated Sucker;[86] the propriety of which name will be evident the moment you examine one of these little fishes alive. Cuvier named the group in which they are found (a group comprising very few species) Discoboles, because the ventral pair of fins are united so as to form a circular disk or saucer, by means of which the fishes have the power of adhering firmly to any solid object larger than the circumference of the disk. Yarrell substitutes the term Cyclopteridæ for the family group; the name Cyclopterus, used for the principal genus, expressing the same thing, that the fins are united in a circular fashion. The word bimaculatus, signifying two-spotted, alludes to two remarkable and conspicuous oval spots of dark purplish brown or red, situated one on each side of the body, just behind the pectoral fin. These spots, being comparatively large, and separated from the general colour of the body by a well-defined white ring, constitute a very striking and beautiful feature in these little fishes.