Physical Structure: Upper head-scales smooth or feebly keeled, imbricate, scarcely enlarged on supraorbital region; a few small spines on each side of the head above the tympanum; latter measuring at least half the diameter of the orbit. Gular sac small; gular scales feebly keeled, as large as dorsals. An oblique fold in front of the shoulder. Dorso-nuchal crest well developed in the male, composed of falciform spines directed backwards, the longest measuring the diameter of the orbit; it gradually decreases in height on the back, being reduced to a mere denticulation on the sacrum. 45-53 scales round the middle of the body; dorsal scales keeled, nearly twice as large as ventrals, all directed upwards and backwards; ventral scales strongly keeled. The adpressed hind limb reaches the tympanum or the posterior border of the orbit; fourth finger slightly longer than the third. Tail a little compressed, at the base with a slightly serrated upper ridge.