Page:Popular Science Monthly Volume 13.djvu/741

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make their acquaintance in a mummified or skeletonized form in museums. It cannot but strike the visitor to any zoölogical collection where the vertebrated section is well represented that the cases devoted to the reptilian group contain forms so divergent as the tortoise and the lizard, the snake and the alligator. If, however, the eye be permitted to pass to the sections on either hand—on the one side, to the amphibious animals, such as the frogs and newts, and on the other, to the birds—it is impossible not to perceive that the contrast is very great. A careless or inexperienced classifier might, perchance, be tempted to relegate the lizard to a place among the amphibia, near to the newts, or vice versa; but the most unobservant of men could never locate a snake among the birds, nor set a turtle or a crocodile on the same shelf with the swallow or the golden-crested wren.

The first and lowest link of the reptilian segment in the great chain of animal existences commences just above the highest of the amphibian assemblage, and is constituted by the river and mud loving tortoises and the turtles of the warmer seas; while the highest now living embraced the Crocodilian family, in whose membership are included the alligators and jacars of the New World, the crocodiles of the Ganges and the gavials of Northern Africa. The gap between these extremes is filled up by various intermediate gradations. To the tortoises succeeds, according to our best classifiers, a powerful race of long-necked ancient mariners—the plesiosaurs—which hunted their prey by the sea-coasts of the geological middle ages, where they left their bones, the sole testimony to the existence of their race, which became extinct before the chalk-cliffs of England were completed, however long ago that may be. After them comes the large group of the true lizards, comprising, along with several extinct orders, the chameleons, the lizards, and the geckos, both the latter being familiar enough to Continental travelers on sunny spots in Southern Europe; the geckos, especially, attracting attention by their habit of running on ceilings and perpendicular walls, by their sucker-formed toes. The next cohort embraces the serpents—the pythons and boas, endued with a power of crushing almost unsurpassed in the animal kingdom; and the rattlesnakes and cobras, carrying swift and certain death in the lightning stroke of their head. The next place is assigned to the great fish-lizards, or ichthyosaurs, which frequented the deeper waters of the same seas as the plesiosaurs, of whose existence also all knowledge would have perished forever, since they died out leaving no representative to continue their line, had not the kindly mud of the bottom preserved for us fragments of their history in their disjointed bones. Advancing from these "dragons of the prime" we again reach the crocodiles, the most specialized of modern reptiles.

Although between the highest and the lowest of these forms there is nothing like the close bond of union which connects the most distantly related of the birds, yet these diverse families have many charac-