Dr. Buckland describes eight distinct species, varying in size from a snipe to a cormorant. Of these, P. crassirostris ([Fig. 105]) and P. brevirostris ([Fig. 106]), were both discovered in the Lias of Solenhofen. P. macronyx belongs to the Lias of Lyme Regis.

The Pterodactyle was, then, a reptile provided with wings somewhat resembling those of Bats, and formed, as in that Mammal, of a membrane which connected the body with the excessively elongated phalanges of the fourth finger, which served to expand the membrane that answered the purposes of a wing. The Pterodactyle of the Liassic period was, as we have seen, an animal of small size; the largest species in the older Lias beds did not exceed ten or twelve inches in length, or the size of a raven, while the later forms found fossil in the Greensand and Wealden beds must have measured more than sixteen feet between the tips of the expanded wings. On the other hand, its head was of enormous dimensions compared with the rest of the body. We cannot admit, therefore, that this animal could really fly, and, like a bird, beat the air. The membranous appendage which connected its long finger with its body was rather a parachute than a wing. It served to moderate the velocity of its descent when it dropped on its prey from a height. Essentially a climber, it could only raise itself by climbing up tall trees or rocks, after the manner of lizards, and throw itself thence to the ground, or upon the lower branches, by making use of its natural parachute.

The ordinary position of the Pterodactyle was probably upon its two hind feet, the lower extremities being adapted for standing and moving on the ground, after the manner of birds. Habitually, perhaps, it perched on trees; it could creep, or climb along rocks and cliffs, or suspend itself from trees, with the assistance of its claws and feet, after the manner of existing Bats. It is even probable, Dr. Buckland thought, that it had the power of swimming and diving, so common to reptiles, and possessed by the Vampyre Bat of the island of Bonin. It is believed that the smaller species lived upon insects, and the larger preyed upon fishes, upon which it could throw itself like the sea-gull.

The most startling feature in the organisation of this animal is the strange combination of two powerful wings attached to the body of a reptile. The imagination of the poets long dwelt on such a combination; the Dragon was a creation of their fancy, and it played a great part in fable and in pagan mythology. The Dragon, or flying reptile, breathing fire and poisoning the air with his fiery breath, had, according to the fable, disputed with man the possession of the earth. Gods and demigods claimed, among their most famous exploits, the glory of having vanquished this powerful and redoubtable monster.

Among the animals of our epoch, only a single reptile is found provided with wings, or digital appendages analogous to the membranous wings of the bats, and which can be compared to the Pterodactyle. This is called the Dragon, one of the Draconidæ, a family of Saurians, which has been described by Daudin, as distinguished by the first six ribs, instead of hooping round the abdomen, extending in nearly a straight line, and sustaining a prolongation of skin which forms a sort of wing analogous to that of the Pterodactyle. Independent of the four feet, this wing sustains the animal, like a parachute, as it leaps from branch to branch; but the creature has no power to beat the air with it as birds do when flying. This reptile lives in the forests of the hottest parts of Africa, and in some isles of the Indian Ocean, especially in Sumatra and Java. The only known species is that figured at page 238 ([Fig. 107]), which comes from the East Indies.

What a strange population was that which occupied the earth at this stage of its history, when the waters were filled with creatures so extraordinary as those whose history we have traced! Plesiosauri and Ichthyosauri filled the seas, upon the surface of which floated innumerable Ammonites in light skiffs, some of them as large as a good-sized cart-wheel, while gigantic Turtles and Crocodiles crawled on the banks of the rivers and lakes. Only one genus of Mammals had yet appeared, but no birds; nothing broke the silence of the air, if we except the breathing of the terrestrial reptiles and the flight of winged insects.

The earth cooled progressively up to the Jurassic period, the rains lost their continuity and abundance, and the pressure of the atmosphere sensibly diminished. All these circumstances favoured the appearance and the multiplication of innumerable species of animals, whose singular forms then showed themselves on the earth. We can scarcely imagine the prodigious quantity of Molluscs and Zoophytes whose remains lie buried in the Jurassic rocks, forming entire strata of immense thickness and extent.

Fig. 107.—Draco volans.