Lizard

II. Amphisbaenidae. Worm-like forms with soft skin divided into squarish segments arranged to form annuli, mere vestiges of scales, no visible eyes or ears, and a very short, bluntly rounded tail; all are pinkish, sometimes more or less dusted with tiny black specks and living in moist, sandy localities, where they con struct subterranean galleries, never appearing on the surface ; America, the Mediterranean countries and Africa. Chirotes of Western Mexico and Lower California is the only genus with ex ternal limbs ; the hind pair are absent and the fore-limbs reduced to short paddles with 5, 4 or 3 clawed fingers. Some of the genera, e.g., Amphisbaena and AMPS, occur both in S. America and Africa and this would appear to indicate that the species living at the present day are but the isolated remnants of a formerly widely distributed group.

I 2. V aranidae.—Monitors ; an Old World family of large lizards with small scales, a long protusible tongue and always with power ful clawed, pentadactyle limbs. This family contains but a single genus V aranus, with about 3o species in Africa, Arabia, Southern Asia and Australia. Some of the species are semiaquatic with laterally flattened tails, others inhabit dry sandy districts but al most all are equally at home on land, in water or among trees. The largest species is the comparatively recently discovered V. komodoensis, the so-called "Dragon" of the East Indian islands of Komodo, Rintja and Flores. This species differs from the majority of monitors in being heavily built with a relatively short tail, so that, although its total length probably never exceeds o feet, a specimen of this size is a very bulky powerful animal; they are diurnal creatures, hiding at night in dens among rocks and active during the day, and like all the other species are strictly carnivorous eating meat of any kind whether freshly killed or not. The Nile Monitor (V. niloticus) an agile wary animal hiding often in burrows on the banks of streams is one of the commonest African species. V. exanthematicus of West Africa is more sluggish and fearless than the Nile Monitor and, unlike that species, relies for defence largely on the use of its powerful whip-like tail; if, however, it does bite the grip may be maintained for as long as half-an-hour. A peculiarity of this species is its habit, when frightened, of rolling over on its back, taking one hind-foot in its mouth and remaining absolutely motionless until the supposed danger has passed. The Kabara Goya of India and the Malayan region (V. salvator) is a large slender species equally at home on land or in the water where it swims by means of the flattened tail, the limbs being closely pressed against the sides. Another Indian species is the Bis-cobra

(V. bengaiensis) which, in common with all the other monitors is erroneously regarded by the natives as poisonous. Australia, possesses a large number of species, the largest being V. gigan teus, a rare species from N. Queensland, and the commonest the Lace Monitor (V. varius). The whole group exhibits great uni formity both as regards structure and colouring; the latter is usually brown, grey or black with dull yellow markings taking the form of transverse bars or rows of rounded ocellar spots.

13. Pygopodidae.

Degenerate serpentiform lizards of Australia, Tasmania and New Guinea, with very long fragile tails, without movable eyelids or fore-limbs, and with the hind-limbs reduced to a flap on either side of the vent. These lizards are not burrowers but appear to live in thick grass or similar vegetation where limbs are of little use and a snake-like method of progression is possi ble. Movement is accomplished by a series of side-to-side, wave like movements which travel from head to tail, a system essen tially similar to that of eels and sea-snakes ; as each undulation travels backwards it presses against the surrounding medium, water or grass, and so drives the animal forwards. Pygopus dis tributed over almost the whole of Australia, may reach a length of 2 feet of which two-thirds belongs to the tail.

14. Helodermatidae.—Lizards with small, tubercle-like scales and sometimes with recurved, grooved teeth. This family con tains only two species, the Gila Monster (Heloderma) of the deserts of Texas, Arizona and Mexico and Lanthanotus of Borneo. The Gila Monsters are the only known poisonous lizards; they are sluggish, heavy-bodied creatures with weak limbs, short stumpy tails and a "warning" colouration of alternating rings of blackish-brown and yellow or pinkish-orange. The poison apparatus consists of a row of glands along the inside of the lower lip (contrast with snakes where the poison glands and fangs are always in the upper jaw) whose openings lie near the bases of the grooved teeth. When the animals bite they delib erately chew the object and in this way a considerable amount of venom is worked into the wounds through the channels of the teeth. The food consists chiefly of small lizards on which the poison acts fairly rapidly but the bite is not, as a rule, fatal to man. Lanthanotus known only from a few specimens from the interior of Borneo is uniformly dull brown in colour and has regular rows of enlarged tubercles; the teeth are not grooved.