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Rh Oligocene. Dracaenosaurus Gervais, Protrachysaurus Stefano, France.

Pliocene. Didosaurus Günther.

Terrestrial or subaquatic lizards from two or three feet to about thirty in length. Epipterygoid and parietal foramen present. Feet pentadactylate, with the primitive phalangeal formula. Sacrals present.

. Terrestrial or subaquatic, reaching a length of about thirty feet (Megalania). Skull more or less elongate, the nostrils rather far back, broadly open. Premaxillae, nasals, and parietals unpaired. Postorbital arch incomplete. Descending plates from the frontals enclose a rhinencephalic chamber. An imperfect joint between angular and splenial. Large palatal openings. Nine cervical, twenty dorsal, vertebrae. Girdles complete. No dermal bones.

This family, exclusively [Australian], African, and Asiatic, includes but one genus, Varanus, with about thirty living species, none more than seven feet in length. Some are subaquatic in habit, seeking the water, in which they swim with freedom by aid of the long flattened tail, to escape their enemies. Their structure is so like that of the following forms of the Dolichosauridae, and especially the Aigialosauridae, that it would seem very probable they all had a common origin in early Cretaceous times. Megalania, from the Pliocene of India [and Pleistocene of Australia], is the largest of all known terrestrial lizards. Unlike most lizards, they have a long protrusible tongue.

Eocene. Saniva Leidy, North America. Paleovaranus Filhol, Proganosaurus Portis, France.

Pliocene. Megalania Owen, India.

Pleistocene. Varanus, India. [Megalania, Australia.]

. Slender aquatic lizards, two or three feet in length, with a relatively small skull, long neck of thirteen