Hawk's-bill Turtle.
"Carvilius Pollio," says Pliny, "a man of great invention in matters pertaining to luxury, was the first who cut the plates of the tortoise for veneering or inlaying." The Romans imported large quantities of this precious article from Egypt, and under the reign of Augustus, the wealthy patricians used even to inlay the doors and columns of their palaces with it. When Alexandria was taken by Julius Cæsar, the warehouses were so full of tortoise-shell that the conqueror proposed to make it the principal ornament of his triumph.
The use of tortoise-shell for the decoration of houses and furniture is long since out of fashion, but it is still in great request for the making of combs and boxes. By steeping it in boiling water it softens, and may then, by a strong pressure, be moulded into any form. When a considerable extent of surface is required, different pieces must be joined together. This is done by scraping thin the edges of the pieces to be united, and laying them over each other while they are in the heated and softened state; strong pressure being then applied, they become completely agglutinated. It is in this way that gold, silver, and other metals for different ornaments are made to adhere to tortoise-shell.
When, at the beginning of the chapter, I mentioned that the lizards had entirely forsaken the ocean, I forgot that the Galapagos Islands in the South Sea, right under the Equator, exclusively possess a maritime animal of this kind, which, from its being the sole existing representative, or dwindled descendant of the giant oceanic saurians of yore, is far too interesting to be passed unnoticed. This lizard is extremely common on all the islands throughout the Archipelago. It lives exclusively on the rocky sea-beaches, and is never found,—at least Mr. Darwin never saw one,—even ten yards inshore. It is a hideous-looking creature, of a dirty black colour, stupid and sluggish in its movements. The usual length of a full-grown one is about a yard, but there are some even four feet long. These lizards were occasionally seen some hundred yards from the shore, swimming about; and Captain Collnett, in his "Voyage," says they go out to sea in shoals to fish. With respect to the object, Mr. Darwin believes he is mistaken; but the fact, stated on such good authority, cannot be doubted. When in the water the animal swims with perfect ease and quickness by a serpentine movement of its body and flattened tail; the legs, during this time, being motionless and closely collapsed on its sides. A seaman of the "Beagle" sank one with a heavy weight attached to it, thinking thus to kill it directly; but when an hour afterwards he drew up the line the lizard was quite active. Their limbs and strong claws are admirably adapted for crawling over the rugged and fissured masses of lava, which every where form the coast. In such situations a group of six or seven of these hideous reptiles may oftentimes be seen on the black rocks, a few feet above the surf, basking in the sun with outstretched legs.
Mr. Darwin opened the stomach of several, and in each case found it largely distended with minced sea-weed, of a kind growing at the bottom of the sea, at some little distance from the coast. The nature of this lizard's food, as well as the structure of its tail, and the certain fact of its having been seen voluntarily swimming out at sea, absolutely prove its aquatic habits; yet there is in this respect one strange anomaly, namely, that when frightened it will not enter the water. From this cause it is easy to drive these lizards down to any little point overhanging the sea, where they will sooner allow a person to catch hold of their tail than jump into the water. They do not seem to have any notion of biting; but when much frightened they squirt a drop of fluid from each nostril. One day Mr. Darwin carried one to a deep pool left by the retiring tide, and threw it in several times as far as he was able. It invariably returned in a direct line to the spot where he stood. It swam near the bottom with a very graceful and rapid movement, and occasionally aided itself over the uneven ground with its feet. As soon as it arrived near the margin, but still being under water, it either tried to conceal itself in the tufts of sea-weed, or it entered some crevice. As soon as it thought the danger was past, it crawled out on the dry rocks and shuffled away as quickly as it could. Mr. Darwin several times caught this same lizard by driving it down to a point, and, though possessed of such perfect powers of diving and swimming, nothing could induce it to enter the water; and as often as he threw it in, it returned in the manner above described.
Perhaps this singular piece of apparent stupidity may be accounted for by the circumstance that this reptile has no enemy whatever on shore, whereas at sea it must often fall a prey to the numerous sharks. Hence, probably urged by a fixed and hereditary instinct that the shore is its place of safety, whatever the emergency may be, it there takes refuge. On a comparison of this singular animal with the true iguanas, the most striking and important discrepancy is in the form of the head. Instead of the long pointed narrow muzzle of those species, we have here a short obtusely truncated head, not so long as it is broad; the mouth consequently is capable of being opened to only a very small extent. From this circumstance, and from the crest on its head, it has received the Latin name of Amblyrhynchus cristatus.
The serpent race, which thrives so abundantly in the tropical forests and morasses, has also its marine representatives in the Indian and Pacific Oceans, where more than fifty species of Hydrophis, Pelamys, and Chersydra have been found. They are distinguished from their terrestrial relations by the flattened form of their tail, the planes of which being directed vertically give it the properties of a powerful oar, in striking the water by lateral oscillations. These sea-snakes always appear to prefer calms, swimming on the still surface in an undulating manner, never raising the head much from the surface, or vaulting out of the water. They dive with facility on the approach of danger, but do not appear to be particularly timid.
