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274 and seem to be as important in classification as those distinguishing the much more typically lizard-like mosasaurs.

No extinct lizards are certainly referable to this tribe, though it is probable that some referred to it will eventually be found to have all the essential characters of the group.

. With the characters of the group.

Oligocene. Rhineura Cope, Aciprion Cope, Diacium Cope, Hyporhina Baur (a postorbital arch). Cremastosaurus Cope, Platyrhachis Cope, North America.

Small, arboreal, perching lizards. Arches complete, the quadrate slender. Postfrontals indistinguishable; premaxillae small or vestigial; no septomaxillae; parietals and frontals unpaired; no parietal foramen; epipterygoids absent or vestigial; palate with openings. Vertebrae procoelous; five cervicals, from eleven to fifteen dorsals, two sacrals, and slender, prehensile tail, the spines sometimes elongated. Clavicles absent or vestigial. Mesopodials much reduced, digital formula 2, 3, 4, 4, 3, the digits in opposable groups of two and three. Abdominal ribs present.

A group composed of about fifty living species confined to Madagascar, Africa, and India. A curious group of insectivorous tree lizards, long famous for their power to change color, and for their peculiar grasping digits. Our paleontological knowledge of them is vague.

. With the characters of the group.

Eocene. Chameleo (Leidy), North America. Prochameleo de Stefano, France.

Triassic. ? Paliguana Broom. South Africa.

Jurassic. ? Saurillus Owen. Jura, England.

Eocene. Enigmatosaurus Nopcsa (de Stefano), Europe. Naocephalus Cope, North America.

Upper Cretaceous. Coniosaurus Owen, Saurospondylus Seeley, England. ? Tylosleus Cope, North America.

Pleistocene. Notiosaurus Owen, ? Patricosaurus Seeley, England.