Page:Natural History, Reptiles.djvu/139

Some of the steps of this beautiful gradation, by which the four long-toed and muscular limbs that mark the Lizard pass away, and leave no trace in the lithe cylindrical Serpent, are thus graphically enumerated by Professor Bell. "From the well-known family of the Scinks (Scincidæ), with their true legs and five-toed feet, down to the Slow-worm (Anguis fragilis) and its immediate congeners, every possible gradation is to be found in the development of the anterior and posterior extremities. Agreeing, as they all do, in the Saurian character of the structure of the head, the consolidation of the bones of the cranium and jaws, and the narrow and confined gape, so different from those parts in the true Serpents, they yet approach the latter in the comparative length of the bodies, and in the gradual diminution and ultimate disappearance of the extremities. In the genus Scincus, for instance, the limbs are already less robust than those of the true Saurians; the two pairs are also more distant from each other, in consequence of the greater comparative elongation of the body. There are as yet five perfect toes on each foot, which, however, are shorter and more even in their relative proportions than in the true Saurians. These deviations become increased in the genus Chalcides, and still more in Seps, which has a very elongated body, the limbs extremely small, and the toes only four or three on each foot. In Monodactylus a further reduction takes place in the development of the limbs, which have dwindled to a mere little undivided finger; they are still, however, four in number; but in the genus Bipes the anterior ones have wholly disappeared,