The Alligatoridæ
Include the Jacares, Alligators, and Caimans.
The Jacares have the head oblong and depressed, with a ridge across the face in front of the eyes; teeth unequal, canines of the lower jaw fitting into a pit in the upper jaw; toes only partially webbed, eyelids fleshy, nostrils separated by a cartilage. Five species are described—namely, J. fissipes, from Tropical America, six feet in length; J. sclerops, from the Brazils; J. Nigra, also from the Brazils; J. punctulatus, with triangular oblong head, muzzle elongated, thin and flat, with a rounded point in front, and a slight enlargement behind the nostrils; J. vallefrons, differing slightly from the above—both natives of the Brazils.
Alligators have the jaws oblong, much depressed, broad and nearly parallel; forehead with a small longitudinal ridge between the orbits; feet fringed, toes half webbed, the outer toes free; nostrils separated by a bony septum rising from the upper edge, muzzle lengthening with age. One species only is known, which is a native of North America; it attains a length of six to seven feet, and is known also as Crocodilus Mississipensis.
The Caimans have the jaws oblong, depressed, rounded, and swollen at the end, without frontal ridges or maxillary pits; teeth unequal, the lower canines fitting into pits in the upper jaw; toes webbed. There are three species described—C. trigonatus, C. palpebrosus, and C. goddeceps, all natives of Tropical America.
The Jacares, Alligators, and Caimans are natives of America, which country is fruitful in other species of the family. C. acutus is also found in Martinique and San Domingo; C. rhombifor, at Cuba; A. palpebrosus, A. sclerops, A. punctulatus, and A. cynocephalus are natives of the southern part of the American Continent; and A. lucius is found in the north.]
The principal characteristics of the American Crocodile are a head one-third its length, and a very short muzzle; teeth unequal in shape and size, the fourth lower tooth being buried in the upper jaw when the mouth is closed; the first teeth of the lower jaw piercing the upper at a certain age, so as to appear through the muzzle when closed. The hinder legs and feet rounded, having neither crest nor indentation on their edges; the intervals of the toes more than half covered with a short membrane, forming semi-palmated feet.
It is generally admitted, as we have stated above, that there are five species of this genera, all exclusively American, the type of which is the Alligator, or Caiman. A. Mississipensis (Gray) belongs properly to North America, through the whole southern extent of which it is found. They are gregarious, living together in large herds in the Mississippi and its southern tributaries; they are also found in the lakes and marshes of Louisiana, Carolina, and even as far north as thirty degrees of north latitude. Alligators do not appear to leave fresh water. During the winter season they bury themselves in the mud of the marshes, and await in a state of torpor the return of spring, which is the signal of their restoration to activity. In the neighbourhood of Bayou Sarah, on the Mississippi, flats of lakes and marshes stretch away to a vast extent on either bank; every year these reservoirs are flooded by the overflow of the river, when they are visited by myriads of fishes. The heat soon partly dries up these lakes, leaving only about two feet deep of water, thus displaying a vast amount of prey ready prepared for the shore birds and Crocodiles. Millions of ibis, herons, cranes, and cormorants wade into the water in pursuit of these fish. In the deepest portions vast quantities of these imprisoned fish accumulate, and these parts are known in the country as the Alligators' holes. Thither these reptiles crowd, pressing one against the other, and they soon thoroughly clear it of the fish which lately were in such dense crowds. As evaporation proceeds and the marshes gradually dry up, the fish are more and more exposed to their voracious enemies. The Alligators pursue and devour them in the water, whilst the ibis destroys those which seek the banks for refuge. Alligators fish chiefly during the night. In the hours of darkness and obscurity they assemble in large herds, chase the fish before them, driving them into some retired creek, where they rejoice their hearts at the expense of the unfortunate finny tribes, which they force into their widely opened mouths by a lateral movement of their tails. On these occasions the clashing of their jaws may be heard at the distance of a mile. Alligators are found by thousands in Mexican waters, and nearly all North American rivers to the south of them. In the beautiful transparent waters of Lake Claro they abound, and are without difficulty seen by the naked human eye. Here they are so closely pressed one against the other that they resemble a raft of trees recently felled, and the resemblance is further increased by the colour of their backs and the bark of a newly-felled tree being identical. In this united and immovable condition, while waiting for their prey, the approach of a boat is disregarded; but they rush with avidity at everything animate which either falls or is thrown into the lake. Many children of poor negro women become a prey to the Caiman in this locality. They rarely, however, pursue men, yet they would not hesitate to devour them if their imprudence has placed them close to their terrible jaws.
The natives of Mexico hunt the Caiman. When they meet an isolated individual asleep, they throw a lasso round its body, and when secured, gag it. After this operation, the victim's career is terminated by hammering on his head. There is another means which the Indians use to capture the Caiman. They provide themselves with four pieces of hard wood about a foot long, and as thick as a man's finger, and pointed at each end; round these they tie a cord in such a manner that, supposing the cord to be an arrow, the four sticks would form the head of it. They then fasten the other end of the cord round a tree, and bait with meat. This device is thrown into the water. When the Caiman snaps at the prey the points of the hook, on straining on the line, penetrate into its flesh. Having waited till the Alligator is dead, it is drawn from the water, when the captors further gratify their dislike and spirit of revenge by breaking its skull with stones and sticks.
Another method of capturing Alligators is practised by the residents on the upper waters of the giant river Orinoco. A tree is bent (generally a bamboo is selected from its elasticity) till the top is brought down to the butt, a bait is then placed on a sharp hook, the line attached to it being fastened securely to the small end of the bent tree, which is caused to relax its position by an ingenious piece of mechanism which gives way the moment the least strain is felt upon the line; the tree-point becoming thus released, straightens itself with great velocity, and drags the victim from the water.
Frequently the Alligator, from constant pursuit and interruption, becomes excessively wary and difficult to destroy; when such is the case, a live bait is sometimes successfully employed. For instance, a Dog with a hook tied to his back is taken in a canoe and dropped in the water; it is seldom the unfortunate cur is permitted to swim far before being seized.
It is currently believed that the Alligator prefers dog-flesh to all others. The negroes on the plantations in the South-Western States of America, by imitating the barking of a dog, frequently lure these reptiles from their hiding-places, when a well-directed bullet terminates their career.
Alligators are very voracious, but, like Serpents and Turtles, they can live a long time without nourishment. In Brown's "Natural History of Jamaica," he asserts that he has known the Caiman to live several months without food. The following experiments have been tried in that island:—The mouth of an Alligator was muzzled by a strong cord, it was then thrown into a reservoir of water. Thus these animals lived a considerable time. They were seen to rise occasionally to the surface of the water, until death came to their rescue. Let us add to this, that Crocodiles bred in captivity in the menagerie of the Museum of Natural History, at Paris, sometimes live for several months without eating.
Fig. 34.—Alligator (Crocodilus lucius).
The female Alligator takes more care of her young than the female Crocodile, properly so called. She conducts them to the water, and in the slimy mud she disgorges her half-digested food for their nourishment.
The true Crocodiles are indigenous to Africa, but they are found also in Manilla and India. Their length of head is almost double its breadth. The fourth tooth of the lower jaw is the longest and largest of all, and passes into an indentation hollowed out in the edge of the upper jaw, becoming visible on the outside. The hind feet have on their external edge a dentated crest, and the interstices of their toes, externally, are palmated.
The principal type is the Common Crocodile, C. vulgaris, which sometimes attains the length of nine or ten feet. The upper part of the body of these reptiles is of an olive green colour spotted with black, and marbled upon the head and neck with the same colour, also the back and tail; two or three broad, oblique black bands are visible upon the flanks of the under part of the body, which is of a yellowish green. Crocodiles abound in Africa. Formerly they were found in all parts of the Nile, but lately it is said that C. vulgaris is no longer to be met with in the Delta, but that it exists in great numbers in the Thebaid and in the Upper Nile. They are also found in the rivers Senegal and Niger, in Caffraria, and in Madagascar. Most authors give them the name of Crocodiles of the Nile. This species are found also in India.
The Crocodile was considered a sacred animal by the ancient Egyptians. In ruins of temples mummies of Crocodiles are still found in a perfect state of preservation. The Romans introduced living Crocodiles at the national games in the Colosseum. At first only five were imported under the ædileship of Scaurus. Under the Emperor Augustus thirty-six were killed in the Circus of Flaminius. Several ancient medals represent this reptile, the body of which perfectly resembles that which now lives in the waters and on the banks of the Nile. There is a truly wonderful fact in the natural history of the Crocodile. Listen to what Herodotus, the father of history, tells us with regard to it:—"When the Crocodile takes his food in the Nile, the interior of its mouth is always covered with bdella (flies). All birds, with one single exception, flee from the Crocodile; but this one, the Nile Bird, Trochylus, far from avoiding it, flies towards the reptile with the greatest eagerness, and renders it a very essential service. Every time the Crocodile goes on shore to sleep, and at the moment when it lies extended with open jaws, the Nile Bird enters the mouth of the terrible animal and delivers it from the bdella which it finds there; the Crocodile shows its recognition of the service, and never harms the bird."
This fact, reported by Herodotus, was long considered to be a fable, but the naturalist, Etienne Geoffroy Saint-Hilaire, who formed part of the commission that General Bonaparte took with him in his expedition into Egypt, had on several occasions opportunities of proving the truth of the historian's narrative.
In a memoir read to the Academy of Science on the 28th of January, 1828, he says, "It is perfectly true that there exists a little bird which flies about, perpetually seeking, even in the mouth of the Crocodile, the insects which form the principal part of its nourishment." This bird, which Geoffroy Saint-Hilaire recognised as the Charadrius Ægyptius of ornithologists, is like a Plover. The bdella, which thus torment the Crocodiles, and even excite them to madness, are no other than our European gnats. Myriads of these insects haunt the banks of the Nile, and when these giants of its waters repose on its margin, warming themselves in the sun, they become the prey of these insignificant pigmies. It is like the war between the Lion and the Mouse, described by La Fontaine. The bdella fly into the Crocodiles' mouths in such numbers that they cover the entire surface of the palate, and form a brownish crust. These little pests pierce the tongues of the reptiles with their stings. It is then that this bird comes into the mouth of the monster to catch them, and deliver it from such innumerable enemies. The Crocodile with one bite could easily destroy the bird, but he knows too well what he owes to this friend to do it an injury. Crocodiles of the Nile are more voracious than the American Alligators. Hasselquist asserts that in Upper Egypt they often devour women who come to draw water from the Nile, as well as children playing upon its banks. Geoffroy Saint-Hilaire says, that in the Thebaid they often met with Arabs wanting an arm or leg, who accused Crocodiles of this mutilation. Sir Samuel Baker also mentions, in his late work on the Nile and its tributaries, the desire of these amphibia for human flesh, and the dread they are held in by the natives. Livingstone, the celebrated traveller, gives the following account of an encounter he had with one of these ferocious animals:—
"The Crocodile," says the celebrated traveller, "makes many victims every year among the children who are so imprudent as to play on the banks of the Liambia when their mothers go to fetch water. The Crocodile stupefies its victim with a blow from its tail, then drags it into the river, where it is soon drowned. In general, when the Crocodile perceives a Man it dives, and furtively glides away from the side which he occupies. Sometimes, on the other hand, it precipitates itself with surprising agility towards the person it has discovered, which may be noticed from the disturbance caused on the surface of the water. An Antelope which is being hunted and takes to the water, in the lagunes of the Barotsé valley, a Man or a Dog who goes there to seek for game, will scarcely fail to be seized by a Crocodile, of whose presence he has not the slightest suspicion. It often happens that, after having danced in the moonlight, the young natives of the river's bank will often plunge into the water in order to refresh themselves, when, being seized by an Alligator, they perish."
[This mode of attack (striking with the tail) is also one of the methods adopted by the Alligator of America for disabling its prey. A friend, on whose veracity I have much dependence, while shooting wild fowl on one of the tributaries of the Lower Mississippi, had the fortune to witness a fight between a Bear and an Alligator. He was called to the scene of the struggle by the noise made by the combatants, in the dry cane, that yielded to their pressure as they fought in each other's embrace. Several times both ceased only to recover breath and fresh energy; at length the Alligator missed striking the foe with its tail, Bruin seized the opportunity, and with all his efforts succeeded in turning the amphibian on its back, where he held him for some minutes, at the same time gnawing one of the fore-shoulders. A final struggle of the now worsted Alligator hurled both into the water, where they disappeared, the disturbed surface telling of the dreadful contest that was being prolonged beneath; after the lapse of over a minute the Bear came up, evidently much fatigued, and swam ashore, my friend forbearing to wound, or possibly kill, the gallant conqueror.]
Crocodiles, it is said, which have never eaten human flesh, are much less dangerous than those that have acquired a taste for it. Mr. Combes states that he was assured by an inhabitant of Khartoum, who had reached the town with the Egyptian troops—that is to say, before the horrors committed by the Desterdar, acting with Mehemet Bey, who had been Governor of the Soudan some time before Mr. Combes's voyage—that the Crocodiles appeared to be quite indifferent to human flesh; but after the many executions by drowning ordered by Mehemet Bey, as he was told by a native whom he interrogated—"since the Nile has been loaded with the carcasses of my brethren"—the monsters which inhabit it have become habituated to substantial food, which they scarcely knew before: so that afterwards those swimming in the river, or even bathing on its banks, were exposed to imminent danger.
Natives of Africa shoot the Crocodile with a gun, or attack it with a barbed javelin, which is thrown by hand, and aimed at the fore-shoulder. Some Egyptians are reported to be daring enough to swim under the Crocodile, and pierce him in the belly with a dagger. The negroes of Senegal are said to be equally expert. If they surprise the animals in parts of the river where there is not sufficient water for them to swim, they attack the monster with a lance; and with their left arm wrapped in a sheet of leather, they commence by aiming with their weapon at the eyes and throat; then they thrust the arm, encased in leather, into its mouth, and, holding it open, their enemy is either suffocated or expires under the wounds received. Traps are also employed successfully for their destruction. In Egypt the natives dig a deep hole in the ordinary route of the Crocodiles, which is easily discovered by the trail they leave in the sand. This hole is covered with branches and strewed with earth. The Crocodile is now alarmed with loud cries, which disturb and drive him back to the river, by the same way that it has left it. As it passes over the treacherous hole it falls in, when it is killed, often with the most brutal cruelty. At other times a thick cord is attached to a large tree, and to the other end of the cord a lamb is bound, held by a protruding hook. The cries of the lamb attract the Crocodile, which, in its attempt to carry off the bait, is taken by the hook.
Still another method for the destruction of these repulsive-looking creatures has been adopted on one or two occasions by our countrymen in India. A dead animal is procured, in its abdomen is placed a loaded shell, to which is attached a wire made fast to an electric battery; when the bait has been seized and carried to the bottom, the shell is exploded, which invariably maims or kills the Crocodile.
The Gavials, or Indian Crocodiles, have long narrow cylindrical muzzles, slightly inflated at the extremity; the teeth are almost the same, both in number and shape, on each jaw, the two first and the fourth of the lower jaw pass into notches or indentations in the upper jaw, and not into holes, as in Crocodiles; the hind legs are dentated and palmated, like those of African Crocodiles. The Gavials are chiefly remarkable for their long head, its type being the Gavial of the Ganges, or Gavial longirostre. It is of a deep watery green colour, having on the upper part numerous irregular brown spots; in the young, the back and limbs are transversely banded with black; the lower part is of a pale whitish yellow; the jaws are marked with brown, the claws are of a clear horn colour. This species is not so carnivorous as the others, and is consequently less dreaded.
The Gavial of the Ganges, G. Gangeticus, is supposed to be the largest of the existing Saurians; its length, as given by Duméril, is seventeen feet four inches.
CHAPTER IV.
CHELONIANS, OR SHIELDED REPTILES.
["The body," as described by Dr. Gray, "is covered with square imbedded plates, generally forming a dorsal and ventral shield united by their margins, leaving only the head, neck, limbs, and tail free, and (in some species, as the Box-Tortoises, Cinasternon, shut up by movable closely-fitting doors) only covered with a scaly skin; the upper shield formed of the ribs united together and adherent to the dorsal vertebræ by a toothed suture, and surrounded by a series of bones forming the edge of the shields; the lower shield, or sternum, formed of four pairs and a central anterior bone; the jaws toothless, covered with a horny bill, rarely hid by fleshy lips; eyelids distinct; drum of the ear visible; legs short and thick; tail conical." "The natural dwelling chamber of the Chelonia consists chiefly," says Professor Owen, "and in the marine species (Chelone) and Mud Turtles (Trionyx) solely, of the floor and the roof; side-walls of variable extent are added to the fresh-water species (Emydians) and Land Tortoises (Testudinians). The whole consists of 'osseous plates,' with superincumbent horny plates, or 'scutes,' except in the Soft or Mud Turtles (Trionyx and Sphargis), in both of which these are wanting."—("Circle of the Sciences.")
These animals, to which a portable stronghold is thus given in compensation for inferior powers of locomotion and defence, are recognisable at a glance from the singular armour with which Nature has provided them. A double shield envelopes all parts of their bodies, only permitting the head, neck, legs, and tail to pass through it: moreover, all these organs can be hidden within this double cuirass by means of a retractile power possessed by the animal. This double armour consists of a carapace, or back-piece, and plastron, or breast-plate, composed of a series of small bones or plates closely united together; the first resulting from the union of the sides and dorsal vertebræ, the plastron, or lower buckler, being only a highly-developed sternum. These organs are merely portions of the skeleton, which, in place of being lodged in the depths of the soft parts, has become the superficies, which is only covered by a thin, dry skin.
This numerous and highly-interesting order of Reptiles, called Chelonia, from χελωνη, a Tortoise, are also called Testudinata, from testudo, the Latin name for a Tortoise, from the double shield in which the bodies of all, whether terrestrial, fresh-water, or marine Tortoises, are enclosed.
The skeleton of the Tortoise is, perhaps, the most extraordinary structure with which we are acquainted. This oddly-organised animal when first seen strikes the beholder with astonishment. The carapace and plastron, with their connecting plates, form a sort of protecting box, in which the animal lives, its head and tail excepted. In the land Turtles the head and feet, which are comparatively senseless, can be withdrawn within the protecting armour. The ribs and sternum are both placed quite on the exterior of the body, so as to form a broad dorsal shield on the upper surface, and an equally strong ventral plate; between these, the limbs and the head can be more or less completely retracted. Nevertheless, the modifications in the arrangement of the elements by which these changes are accomplished are of the simplest nature. In the common Tortoise, Emys Europæus, the vertebræ of the neck and tail being connected together in the ordinary manner, the neck and caudal region of the spine present their usual flexibility, but the dorsal vertebræ are strangely distorted, the upper arch being disproportionately developed, while the bodies remain almost in a rudimentary state; the spinous processes of these vertebræ are flattened and converted into broad osseous plates, which form a longitudinal series along the centre of the back, and connected together by means of sutures. The ribs are changed into broad flat bones firmly united by sutures to each other, and also to the lateral margins of the spinous processes of the vertebræ, so that they form together a single broad plate; the heads of the ribs are feebly developed, and the intervals between them and the bodies of the vertebræ filled up with ligament. The margin of the shield thus formed by the dorsal ribs is further enlarged by a third set of flat bones fixed by sutures around the whole circumference of the carapace.
The plastron, or ventral plate, is made up of nine pieces, of which eight are arranged in pairs; but the ninth, which is always placed between the four pieces composing the two anterior pairs, is single, and occupies the mesial line. The bones of the shoulder and hip are placed within the thorax, and articulated to the sides of the vertebral column.
Of this vertebral column in these extraordinary animals, Professor Owen remarks that the manifold modifications of the framework which render it a portable abode, appear to have been given as a compensation for inferior powers of locomotion, and the absence of offensive weapons. But with all its modifications, the same number of pieces are found in the bony skeleton as in other ordinary vertebratæ, the form and volume of many of these pieces being alone changed.
The skin which covers the body of these animals sometimes preserves its softness, being altogether devoid of scales; but in nearly all the species it is covered with horny scales of great consistency. Upon the plastron and carapace these scales form large plates, the arrangements and appearances of which vary in different species, some of them being often remarkably beautiful. The material which bears the name of Tortoise-shell forms an important article of commerce.
Aristotle mentions three groups of Tortoises; namely, χελωη χερσαια, or Land Tortoises; θαλαττια, or Sea Tortoises; and Εωhυς, or Fresh-water Tortoises. Cuvier divides them into five sub-genera:—1, Land Tortoises, Testudo (Brogniart); 2, Fresh-water Tortoises, Emydes (Brogniart); 3, Marine Tortoises, Chelque (Cuvier); 4, Chelydes, Testudo fimbriata; 5, Soft Tortoises, Trionyx (Geoffrey)—in which he is followed by Dr. Gray in the British Museum Catalogue, who makes them the third order of Reptiles in his arrangement as follows:—
| I. Testudinidæ. |
|---|
| Testudo, Chersina, Kinixys, Pyxis. |
| II. Emydidæ. |
| Geoemyda, Emys, Cyclemys, Malaclemys, Cistudo, Kinosternon, Chelydra, Platysternum. |
| III. Chelydidæ. |
| Sternotherus, Pelomedusa, Hydraspis, Chelymys, Phrynops, Chelodina, Hydromedusa, Chelys, Peltocephalus, Padocnemis. |
| IV. Trionycidæ. |
| Trionyx, Emyda. |
| V. Cheloniadæ. |
| Sphargis, Chelonia, Caretta, Casuana. |
In the valuable "Erpétologie" of Messrs. Duméril and Bibron, the Chelonians are divided into—1, Land Tortoises, Chersites; 2, Marsh Tortoises, Elodites; 3, River Tortoises, Potamites; 4, Sea Tortoises, or Turtles, Thalassites.
This arrangement being the most simple, is adopted as best adapted to our purpose.]