| BOX TORTOISE |
| (Cistuda carolina) (After Babcock. Boston Society of Natural History) |
The typical and most numerous of these belong to the genus Testudo, with about forty species scattered over all warm or temperate parts of the world except Australasia. Typically grazers and fruit eaters, they occasionally vary their diet with worms, snails, and insects. The eggs are hard-shelled, and the males are usually smaller than their mates. Most land tortoises hibernate in the ground during the cold half of the year, or they æstivate during the hot and dry seasons when in the tropics, but this is not an invariable rule. Several species of these land tortoises are common and well known in Europe and also in India, and are often kept as pets. They show considerable intelligence, and are decidedly fond of listening to music. Our best known American representative is the "gopher" (Xerobates polyphemus) of Florida, Georgia, and Texas. This turtle is nearly a foot long, with a high, rounded shell, dull brown in color, and the forefeet covered with hornlike scales and some spines—an armature for digging. The deserts along the Mexican border have several local species.
In this family belong the "gigantic" tortoises of the islands east of Africa and west of South America, now all but extinct, save a few in captivity in zoölogical gardens. In fact they differ from ordinary land tortoises mainly in size and in such minor points as distinguish the various species; some of them, indeed, are not excessive in bulk. The largest on record is a male of T. daudini, of South Aldabra, whose shell was sixty-seven inches long, and whose living weight was 500 pounds. A fossil species of the late Miocene in India had a shell six feet long, and then and later tortoises almost as big inhabited both Europe and North America, and more recently Madagascar. Their survivors are now restricted to two widely separated regions—the Galapagos Islands, 600 miles off the coast of Ecuador, and the Mascarenes and other western islands in the Indian Ocean. The most interesting thing about this matter is the presence of these tortoises on these widely scattered islands, and the effects of their isolation. It must be noted that when discovered by European voyagers no one of these islands, except the Comoros, was inhabited by men, and none had any large or harmful beasts of prey.
On these peaceful islands plenty of food, an equable climate, and absence of enemies, enabled the tortoises in vast numbers to grow to a size impossible to their relatives on the mainlands. "Scattered over the many islands they were prevented from interbreeding, and thus it has come to pass that not only every group of islands, but, in the case of the Galapagos, almost every island has, or had, its own particular kind." How did these huge chelonians get to these islands? None like them is found on any continent at present, although they had a wide distribution in geological ages. We must conclude that those of the Madagascar region, at least, are the descendants of tortoises once populating "Lemuria," that land area which until mid-Tertiary time occupied the region of the western Indian Ocean, and of which the existing islands are the remains. A similar theory, for which there is geological evidence, may account for the survival of the Galapagos giant tortoises after those of the mainland had died off.
The next family is that of the big sea turtles (Chelonidæ), such as the green turtle, whose flesh is so highly prized a substance for delicate soups (but almost all turtle flesh is good eating), the hawksbill and the loggerhead. They abound in all warm seas, and reach a large size, the green turtle often having a shell three to four feet long, but smooth, while that of the hawksbill is covered with horny plates with high keels and an overlapping arrangement, which are the tortoise shell of commerce. The green turtle is wholly vegetarian in diet, feeding on the large seaweeds, while the others are carnivorous, devouring fishes, mollusks, etc. All three resort in summer to sandy beaches, dig holes, and bury a great quantity of eggs.
There remains a large group of fresh-water turtles, distinguished, in addition to other important structural peculiarities, by the fact that they withdraw the head under the shell by a sidewise bending of the long neck. They are entirely carnivorous, and occur in all tropical and some temperate countries, the ferocious "soft shells" of the Mississippi Valley and northeastward belonging here. A very curious one is the matamata of Guiana and northern Brazil, the biggest of its tribe, becoming more than three feet long. It gets its living by stratagem rather than by activity. The back of its shell is so roughened by coarse bosses that it looks like the bark on an old log, and ragged flaps of skin project from head and neck. These are kept in constant motion, and attract the attention of passing fishes and other creatures, whose curiosity often takes them too near the treacherous jaws of the concealed monster.
Our list of turtles ends with the one probably of most importance to mankind of all the kinds in the world. This is the "arrau" of the Amazon and Orinoco basins, where it is very abundant, and not only an essential element in the subsistence of the native Indians, but of great commercial importance on account of the eggs, which are periodically collected in enormous quantities, chiefly for their oil. This oil is eaten, like the eggs themselves, or is used for burning in lamps, or as an addition to tar. The turtles are likewise eaten by man and beast. This turtle is large, sometimes three feet long; and it deposits a great number of soft-shelled eggs in the sand.
| HORNED DINOSAUR |
| (Monoclonius nasicornus) |
| Skeleton restored from bones found in the Red Deer River region, Canada. (American Museum of Natural History) |