[19] The Petrel is similarly used in the Faroe Islands. (See ante, p. 234.) It may, therefore, be called the Candle Bird.
[20] Dr. Richardson. The Huro is reported by Pallas to attain a weight of nearly three thousand pounds, and a length exceeding thirty feet.
THE TREE-CLIMBING CRAB.
THE transition from the ordinary mode of the locomotion of fishes by swimming to that of climbing has been ably illustrated by the Rev. Dr. Buckland, who showed, in a communication to the Ashmolean Society, in 1843, that the fins in certain genera perform the functions of feet and wings. Thus, "fishing-frogs" have the fins converted into feet, or paddles, by means of which they have the power of crawling or hopping on sand and mud; and another species can live three days out of the water, and walk upon dry land. The climbing perch of the Indian rivers is known to live a long time in the air, and to climb up the stems of palm-trees in pursuit of flies, by means of spinous projections on its gill-covers. Fishes of the silurus family have a bony enlargement of the first ray of the pectoral fin, which is also armed with spines; and this is not only an offensive and defensive weapon, but enables the fish to walk along the bottom of the fresh waters which it inhabits. The flying-fishes are notorious examples of the conversion of fins into an organ of movement in the air. M. Deslongchamps has published, in the "Transactions of the Linnæan Society of Normandy," 1842, a curious account of the movements of the gurnard at the bottom of the sea. In 1839, he observed these movements in one of the artificial fishing-ponds, or fishing-traps, surrounded by nets, on the shore of Normandy. He saw a score of gurnards closing their fins against their sides, like the wing of a fly in repose, and without any movement of their tails, walking along the bottom by means of six free rays, three on each pectoral fin, which they placed successively on the ground. They moved rapidly forwards, backwards, to the right and left, groping in all directions with these rays, as if in search of small crabs. Their great heads and bodies seemed to throw hardly any weight on the slender rays, or feet, being suspended in water, and having their weight further diminished by their swimming-bladder. During these movements the gurnards resembled insects moving along the sand. When M. Deslongchamps moved in the water, the fish swam away rapidly to the extremity of the pond; when he stood still, they resumed their ambulatory movement, and came between his legs. On dissection, we find these three anterior rays of the pectoral fins to be supported each with strong muscular apparatus to direct their movements, apart from the muscles that are connected with the smaller rays of the pectoral fin.
Dr. Buckland states that Miss Potts, of Chester, had sent to him a flagstone from a coalshaft at Mostyn, bearing impressions which he supposed to be the trackway of some fish crawling along the bottom by means of the anterior rays of its pectoral fins. There were no indications of feet, but only scratches, symmetrically disposed on each side of a space that may have been covered by the body of the fish whilst making progress, by pressing its fin-bones on the bottom. As yet, no footsteps of reptiles, or of any animals more highly organized than fishes, have been found in strata older than those which belong to the new red sandstone. The abundant remains of fossil fishes, armed with strong bony spines, and of other fishes allied to the gurnard, in strata of the carboniferous and old red sandstone series, would lead us to expect the frequent occurrence of impressions made by their locomotive organs on the bottoms of the ancient waters in which they lived. Dr. Buckland proposed to designate these petrified traces or trackways of ancient fishes by the term of fish-tracks.
Crabs and Lobsters are strange creatures: strange in their configurations; strange in the transmutations which they exhibit from the egg to maturity; strange in the process they undergo of casting off, not only their shell, but the covering of their eyes, of their long horns, and even the lining of their tooth-furnished stomach; strange, also, are they in their manners and habits. Many a reader, in wandering along the sea-shore, may have disturbed little colonies of Crabs quietly nestling in fancied security amidst banks of slimy sea-weed; and in the nooks and recesses of the coast, the shallows, and strips of land left dry at ebb-tide, may be seen numbers of little, or perchance large, Crabs, some concealed in snug lurking-places, others tripping, with a quick side-long movement, over the beach, alarmed by the advance of an unwelcome intruder. Some are exclusively tenants of the water, have feet formed like paddles for swimming, and never venture on land; others seem to love the air and sunshine, and enjoy an excursion, not without hopes of finding an acceptable repast, over the oozy sands; some, equally fond of the shore and shallow water, appropriate to themselves the shells of periwinkles, whelks, &c., and there live in a sort of castle, which they drag about with them on their excursions, changing it for a larger as they increase in measure of growth. They vary in size from microscopic animalcules to the gigantic King Crab: [21] to the former, the luminosity of the ocean, or of the foam before the prows of vessels, is, to a great extent, attributable, each minute creature glowing with phosphoric light.