The Launces are distinguished from the eels by their large gill openings, and their caudal fin being separated from their dorsal and anal fins. The common Sand Launce abounds on many parts of our shore. On account of its silvery brightness it is highly esteemed by the fishermen as bait for their hooks, and its remarkable habit of burrowing in the sand as the tide recedes affords easy means of capture. While underground, it most likely gets hold of many an unfortunate lob-worm, mollusc, or crustacean, but on emerging from its retreat it is in its turn preyed upon by the larger fishes. On a calm evening it is an interesting sight to see the surface of the water broken by the repeated plunges of the voracious mackerel as they burst upon the launces from beneath. On the sands at Portobello, near Edinburgh, people of all ages may be seen when the tide is out diligently searching for the sand launce, and raking them out with iron hooks. On the south coast of Devonshire, where the sand launces are extremely plentiful, the fishermen employ a small seine with a fine mesh, and are frequently so successful that six or seven bushels are taken at one haul. The usual length of the sand launce is from five to seven inches. In many localities it is prepared for table, and considered a great delicacy.
Although the Lamprey essentially differs from the eel in the formation of its gills, the softness of its cartilaginous skeleton, and its funnel-shaped mouth provided with sharp teeth, disposed in circles, yet it resembles it closely in its outward form. Its colour is generally a dull brownish olive, clouded with yellowish-white variegations; the fins are tinged with dull orange, and the tail with blue. The Marine or Sea Lamprey inhabits the ocean, but ascends the rivers in spring. Though capable of swimming with considerable vigour and rapidity, it is more commonly seen attached by the mouth to some large stone or other substance, the body hanging at rest, or obeying the motion of the current. Its power of adhesion is so great that a weight of more than twelve pounds may be raised without forcing the fish to quit its hold. Like the eel, it is remarkably tenacious of life, the head strongly attaching itself for several hours to a stone, though by far the greater part of the body be cut away from it. The lamprey is still considered as a delicacy; every schoolboy knows that King Henry I. died of an indigestion caused by this favourite dish; and the town of Gloucester still sends every Christmas a lamprey-pie to Queen Victoria, such as it was wont to offer to its sovereign in the days of the Plantagenets and Tudors.
Myxine.
The Myxine, Glutinous Hag, or Borer, bears a near resemblance to the lamprey, but stands upon a much inferior degree of organisation, having no eyes—(the sole example of blindness among fishes), and a still softer skeleton, so that, when boiled, it almost entirely dissolves into mucus. In the lamprey and myxine, the branchial cells, which admit water, are lined by the delicate membrane through which the blood is aërated. In the former, however, the external apertures of the branchial cells are placed on the side of the neck; while in the myxine, which feeds on the internal parts of its prey, and buries its head and part of its body in the flesh, the openings of the respiratory organs are removed sufficiently far back to admit of the respiration going on while the animal's head is so inserted. Thus, even in this lowest and meanest of all vertebrate animals, we find a remarkable adaptation of its construction to its wants, and the proof that it has been as well taken care of by its Creator as the highest organised creatures of its class.
Porcupine-Fish—(Diodon hystrix.) | Globe-Fish. |
Short Sun-Fish.—(Orthagoriscus Mola.) | Trunk-Fish.—(Ostracion triqueter.) |
File-Fish.—(Balistes erythropterus.)
One of the most remarkable orders of fishes is that of the Plectognaths, which are distinguished by having the superior maxillary bones and the intermaxillaries soldered together so as to render the upper jaw immovable, or incapable of projection. Among the Plectognaths, we find among others the prickly Globe-fishes and sea-porcupines; the curiously-shaped Sun-fishes, all head and no body; the Ostracions or Trunk-fishes, clothed like the armadillos in a defensive coat of mail, leaving only the tail, fins, mouth, and a small portion of the gill-opening, capable of motion; and the gorgeous Balistæ or File-fishes, which owe their family-name to the peculiar structure of their first dorsal fin. The first and strongest spine of this organ is studded up the front with numerous small projections, which, under the microscope, look like so many points of enamel or pearl arising from the surface of the bone and giving it the appearance of a file. The second smaller spine has in the fore part of its base a projection which, when the spines are elevated, locks into a corresponding notch in the posterior base of the first spine, and fixes it like the trigger of a gun-lock; from which the fish is called in Italy pesce balestra, or the cross-bow fish. The strong spine cannot be forced down till the small one has been first depressed and the catch disengaged.