_Gerrhonotus_, 8 species, in mountainous countries, from British Columbia to Costa Rica; like _Diploglossus s. Celestus_ of Mexico, the Antilles and Central America, with well-developed limbs, but with a lateral fold. _Anguis fragilis_ and two species of _Ophiosaurus_ are the only members of this family which are not American, and even the third species of _Ophiosaurus_, _O. ventralis_, lives in the United States. _Ophiosaurus s. Pseudopus_, the glass-snake, from Morocco and the Balkan peninsula to Burma and Fokien; also in the U.S.A., with the limbs reduced to a pair of tiny spikes near the vent, and a lateral fold along the snake-like body. _Anguis_, with its sole species fragilis, the slow-worm or blind-worm, is devoid of a lateral fold, and the limbs are entirely absent. Europe, Algeria and western Asia. Family 5. _Helodermatidae_, with _Heloderma_ of Arizona and Mexico, and _Lanthanotus_ of Borneo.--The teeth of _Heloderma_ are recurved, with slightly swollen bases, loosely attached to the inner edge of the jaws; each tooth is grooved, and those of the lower jaw are in close vicinity of the series of labial glands which secrete a poison; the only instance among lizards.[2] Limbs well developed. Tongue resembling that of the _Anguidae_. The skin of the upper surface is granular, with many irregular bony tubercles which give it an ugly warty look. _H. horridum_ in Mexico, and _H. suspectum_, the gila monster, in the hot and sandy lowlands of the Gila basin. The animal, which reaches a length of more than 2 ft., is blackish-brown and yellow or orange, and on the thick tail these "warning colours" are arranged in alternate rings. Small animals are probably paralyzed or killed by the bite, the poison being effective enough to produce severe symptoms even in man. The Zapotecs, who call the creature Talachini, and other tribes of Mexico have endowed it with fabulous properties and fear it more than the most poisonous snakes. _Lanthanotus corneensis_, of which only a few specimens are known, is apparently closely allied to _Heloderma_, although the teeth are not grooved, osteoderms are absent and probably also the poison glands. Family 6. _Aniellidae._--One genus, _Aniella_, with a few worm- or snake-shaped species in California, which seem to be degraded forms of _Anguidae_. The eyes and ears are concealed, the limbs are entirely absent, body and tail covered with soft, imbricating scales. The tongue is villose, smooth, bifid anteriorly. The few teeth are recurved, with swollen bases. The skull is much reduced. Total length of _A. pulchra_ up to 8 in. Family 7. _Zonuridae._--Pleurodont; tongue short, villose, scarcely protractile, feebly nicked at the tip. With osteoderms at least upon the skull, where they roof in the temporal region. Africa and Madagascar.