The Pythons are large Serpents of Asia and Africa. They live in marshy places, and near the margins of rivers. They are non-venemous, but possessed of immense muscular power, which enables some of the species to kill, by constriction, animals of much larger circumference than themselves.
Aristotle tells us of immense Lybian Serpents, so large that they pursued and upset some of the triremes of voyagers visiting that coast. Virgil's Laocoon, so vividly represented in the well-known marble group, owes its origin, no doubt, to the descriptions current of constricting Serpents. Quoting Livy, Valerius Maximus relates the alarm into which the Roman army, under Regulus, was thrown by an enormous Serpent, having its lair on the banks of the Bagradus, near Utica. This Serpent Pliny speaks of as being a hundred and twenty feet long. But, without multiplying instances to which time has lent its fabulous aid, and coming to more modern times, Bontius speaks of Serpents in the Asiatic islands as beings so various that he despairs of even enumerating them all. "The great ones," he says, "sometimes exceed thirty-six feet, and have such capacity of throat and stomach, that they swallow entire Boars." Adding that he knew persons who had partaken of a Hog cut out of the stomach of a Serpent of this kind. "They are not poisonous," he adds, "but they strangle by powerfully applying their folds round the body of their prey." Mr. M'Leod, in his interesting voyage of the Alceste, states that during a captivity of some months at Whidah, on the coast of Africa, he had opportunities of observing Serpents double this length, one of which engaged a negro servant of the governor of Fort William in its coil, and very nearly succeeded in crushing him to death. There can be no doubt that the length is here much exaggerated. About thirty feet is the utmost length attained by the most gigantic Serpents of which we possess accurate knowledge.
The body of the Python is large and round. They live on trees in warm damp places, on the banks of streams or water-courses, and attack the animals which come there to slake their thirst. Hanging by the tail to the trunk of a tree they remain immovable in their ambush until their opportunity comes, when they dart upon their prey, fold their bodies round it with amazing rapidity, and crush it in their monstrous folds. Animals as large as Gazelles, and even larger, thus become their victims. Their jaws are extremely distensible, as we have seen; for, having neither breast-bone nor false sides, they can easily increase the diameter of the opening, so as to swallow the most voluminous prey.
The Ophidians (as we have seen) surpass all other Reptiles in the number of their vertebræ, with incomplete hæmal arches; these constitute the skeleton of the long, slender, limbless trunk. All these vertebræ coalesce with one another, and are articulated together by ball-and-socket joints. Besides this articulation to the centrum, the vertebræ of Ophidians articulate with each other by means of joints which interlock by parts reciprocally receiving and entering one another, like the tenon-and-mortise joint in carpentry. "The vertebral ribs have an oblong articular surface, concave above and almost flat below, in the Python. They have a large medullary cavity, with dense but thin walls, with a fine cancellated structure at their articular ends. Their lower end supports a short cartilaginous membrane, closing the hæmal arch, which is attached to the broad and stiff abdominal scute. These scutes, alternately raised and depressed by muscles attached to the ribs and integuments, aid in the gliding movement of serpents."
The peculiar motion of Snakes was first noted by Sir Joseph Banks, and commented on by Sir Everard Home. Sir Joseph was observing a Coluber of unusual size, and thought he saw its ribs come forward in succession, like the feet of a caterpillar. To test this, he placed his hand under the animal, the ends of the ribs were distinctly felt pressing upon the surface in regular succession, leaving no doubt that the ribs formed so many pairs of levers, by means of which it moves its body from place to place.
The muscles which bring forward these ribs, according to Sir Everard, consists of five sets. One from the transverse process of each vertebra and the rib immediately behind it, which rib is attached to the next vertebra. The next set goes from the rib near the spine, and passes over two ribs, sending a slip to each, and is inserted into a third, a slip connecting it with the next muscle in succession. Under this is a third set, issuing from the posterior side of each rib, passing over two ribs, and sending a lateral slip to the next muscle, and is also inserted in the third rib behind. And so on throughout the five sets of muscles.
On the inside of the chest there is a strong set of muscles attached to the anterior surface of each vertebra, and passing obliquely forward over four ribs is inserted into the fifth one only in the centre. From this part of each rib a strong flat muscle comes forward on each side, before the viscera, forming the abdominal muscles and uniting in a middle tendon, so that the lower half of each rib which is beyond the origin of this muscle, and which is only laterally connected to it by a loose cellular membrane, is external to the belly of the animal, and is used for the purpose of progressive motion, while that half of each rib which is next the spine, as far as the lungs extend, is employed in respiration.
These observations of Sir Everard Home apply to all Snakes; but the muscles were compared with a skeleton of the Boa-constrictor in the Hunterian Museum, which is thirteen feet nine inches in length. The habit of attaching themselves to trees, and holding on by the tail, their heads and bodies floating listlessly on some sedgy river, is explained by the structure of the tail. Dr. Meyer has minutely described the manner in which they hook themselves on to a tree, which gives them the power of a double fulcrum. The apparatus which gives this power is a spur or nail on each side of the vent in the Pythonidæ, in which the anatomist discovered the elements of an unguinal phalanx articulated with another bone much stronger, which is concealed under the skin.
Following the arrangement of the Pythonidæ, adopted by Dr. J. E. Gray in the Catalogue of the British Museum, we find:—
I. Morelia, having a strong prehensile tail, distinct head, truncate muzzle, crown of the head with small shield-like plates. Of this genus there are two species. The Diamond Snake (M. spilotes), a native of Australia, and of a bluish-black colour; and the Carpet Snake (M. variegata), from Port Essington and Swan River. It is whitish, with irregular black-edged olive spots, and an olive head, with two or three white spots in the centre of the crown.