They are said to be completely deaf; so much is certain, that they do not perceive a person even when walking close behind them. Mr. Darwin often amused himself by overtaking the slow and monstrous creatures, who, as soon as he had passed them, instantly withdrew their head and legs, and fell flat down with a loud hiss and heavy noise as if touched by lightning. He then mounted upon their back, and on giving them a smart slap or two on the hind part of their carapace, they rose and leisurely proceeded with their learned freight, the author of ‘Origin of Species’ finding it very difficult to maintain his equilibrium on this strange beast of burthen.
It is a remarkable fact, that though the land-tortoises are scattered in many places over the warmer regions of the globe, and even extend as far as Patagonia and the south of Europe, yet not a single one has hitherto been found in Australia, where, equally strange to say, no indigenous monkey exists.
MARSH TORTOISE. (EMYS PICTA.)
The marsh tortoises, or Emydæ, have their chief seat in tropical America and the Indian Archipelago, where an abundance of swamps, lagoons, lakes, pools, and gently-flowing rivers favours the increase of their numbers. In the month of September, as soon as the sand-banks begin to be uncovered, the females deposit their eggs, scraping hollows of a considerable depth, covering them over carefully, smoothing and beating down the sand, and then walking across and across the place in various directions, for the purpose of concealment. There are such numbers of them, that some beaches are almost one mass of eggs beneath the surface, and here the Indians come to make oil. A canoe is filled with the eggs, which are all broken and mashed up together. The oil rises to the top, and is skimmed off and boiled, when it will keep, and is used both for light and for cooking. During this operation, the neighbouring strand swarms with carrion vultures, and the smell of the offal attracts also a number of alligators, eager to come in for their share of the feast. Millions of eggs are thus annually destroyed, and of those that remain a very small portion only arrives at maturity. When the young tortoises issue from the egg and run to the water, many enemies are awaiting them. Great alligators open their jaws, and swallow them by hundreds; the jaguars and the smaller felidæ from the forest come to feed upon them; eagles and buzzards and the great wood ibises attend the feast, and when they have escaped all these, there are many ravenous fishes which seize them in the stream.
The marsh-tortoises may be said to form the connecting link between the eminently aquatic marine and river chelonians and the land-tortoises, as the formation of their feet, armed with sharp claws or crooked nails, and furnished with a kind of flexible web, connecting their distinct and movable toes, allows them both to advance much quicker on the dry land than the latter, and to swim rapidly either on the surface or in the depth of the waters.
Endowed with more rapid powers of locomotion, they are not vegetarians, like the land-tortoises, but chiefly live on mollusks, fishes, frogs, toads, and annelides.
The river-tortoises differ in many respects from the sea-turtles, although formed like them for a purely aquatic life. In both families the extremities are complete fins, serving as oars, but the fore feet of the river-tortoises are not double the length of the hind feet, as we find in the marine chelonians; and while the latter have a short apoplectic neck, that of the river-tortoise is generally very long, and surmounted by a small and narrow head. The river-tortoises are exclusively confined to the warmer countries of the globe, and sometimes weigh as much as seventy pounds. It seems that during the night, and when they fancy themselves secure from danger, they repose upon the small river islands, or on rocks and trunks of trees that have fallen on the banks, or are drifted along by the current, and instantly plunge again into the water at the sight of man or at the least alarming noise. They are extremely voracious, and being very active swimmers, kill numbers of fish and reptiles. When they wish to seize their food or to defend themselves, they dart forwards their head and long neck with the velocity of lightning, and are said in this manner to surprise and seize even small birds that incautiously fly too near the surface of the water. They bite lustily with their sharp beak, never quitting their hold till they have fairly scooped out the morsel, so that the fishermen stand in great awe of their powerful mandibles, and generally cut off their head as soon as they are caught, rightly judging this to be the most radical means to prevent any further mischief. The Indians of the Amazons catch them either with the hook, net, or arrow. The last is the most ingenious method, and requires the most skill. The tortoise never shows its back above water, only rising to breathe, which it does by protruding its nostrils almost imperceptibly above the surface. The Indian’s keen eye perceives this, even at a considerable distance, but an arrow shot obliquely would glance off the smooth flat shell, so he shoots up into the air with such accurate judgment that the arrow falls nearly vertically upon the shell, which it penetrates, and remains securely fixed in the tortoise’s back. The head of the arrow fits loosely on to the shaft, and is connected with it by a long fine cord, carefully wound round it; as the tortoise dives they separate, the light shaft forming a float or buoy which the Indian secures, and by the attached cord draws the prize up into his canoe. In this manner almost all the tortoises sold in the small settlements on the Amazons are procured, and the little square vertical hole of the arrow-head may generally be seen in the shell.
The turtles, which are likewise inhabitants of the warmer latitudes, though sometimes a strange erratic propensity or mischance will carry them as far from their usual haunts as the North Sea, have, as we all know, a far greater commercial and gastronomic value than all the rest of the tortoise tribes.[28]
During the Brazilian summer (December, January, February), colossal turtles are seen everywhere swimming about along the coast, raising their thick round heads above the water, and waiting for the approach of night to land. The neighbouring Indians are their bitterest enemies, killing them whenever they can. Thus these dreary sand coasts, bounded on one side by the ocean and on the other by gloomy primæval forests, offer on all sides pictures of destruction, for the bones and shells of slaughtered turtles everywhere bestrew the ground. Two parallel grooves indicate the path of the turtle after landing; they are the marks of the four large and long fin-shaped feet or paddles, and between them may be seen a broad furrow where the heavy body trailed along the ground. On following these traces about thirty or forty yards shore-upwards, the huge animal may be found sitting in a flat excavation formed by its circular movements, and in which one half of its body is imbedded. It allows itself to be handled on all sides without making the least attempt to move away, being probably taught by instinct how useless all endeavours to escape would be. A blowing or snorting like that of a goose when any one approaches its nest, at the same time inflating its neck a little, are the sole signs of defence which it exhibits.