BOA  , a name formerly applied to all large serpents which, devoid of

poison fangs, kill their prey by constriction; but now confined to that subfamily of the Boidae which are devoid of teeth in the praemaxilla and are without supraorbital bones . The others are known as pythons (q.v.) . The true boas comprise some forty species; most of them are American, but the genus Eryx inhabits North Africa, Greece and south-western Asia; the genus Enygrus ranges from New Guinea to the Fiji; Casarea dussumieri is restricted to Round Island, near Mauritius; and two species of Boa and one of Corallus represent this subfamily in Madagascar, while all the other boas live in America, chiefly in tropical parts . All Boidae possess vestiges of pelvis and hind limbs, appearing externally as claw-like spurs on each side of the vent, but they are so small that they are practically without function in climbing . The usually short tail is prehensile . One of the commonest species of the genus Boa is the Boa constrictor, which has a wide range from tropical Mexico to Brazil . The head is covered with small scales, only one of the preoculars being enlarged . The general colour is a delicate pale brown, with about a dozen and a half darker cross-bars, which are often connected by a still darker dorso-lateral streak, enclosing large oval spots . On each side is a series of large dark brown spots with light centres . On the tail the markings become bolder, brick red with black and yellow . The under parts are yellowish with black dots . This species rarely reaches a length of more than 10 ft .

It climbs well, prefers open

forest in the neighbourhood of water, is often found in plantations where it retires into a hole in the ground, and lives chiefly on birds and small mammals . Like most true boas, it is of a very gentle disposition and easily domesticates itself in the palm or reed thatched huts of the natives, where it hunts the rats during the night . The term' " boa " is applied by analogy to a long article of women's dress wound round the neck .