The Skin Sense Organs of Some Iguanian Lizards

The structure and topography of cutaneous receptors of 21 species of iguanian lizards were studied using histology and scanning electron microscopy. Sense with hairs are found in the integument of Ceratophora, Draco, Phrynocephalus, Stellio, and Trapelus (agamids), and in Anolis, Chal- arodon and Oplurus (iguanids). Sense without hairs are found in the integument of Physignathus (agamid) and Sceloporus (iguanid). The chameleons have generalized epidermal receptors with simplified structure. Familial differences were observed in the numbers of receptors on the scales of the head and the tail: iguanids have 5-7 times more receptors than agamids. Physignathus differs from other agamids in the morphology, size, and number of receptors. These receptors are hypothesized to serve several functions (as mechano- and thermoreceptors, and possibly sensitivity to humidity). Integumental sense were first de- scribed for reptiles in 1868 by Leydig in the lizard genera Lacerta and Anguis, and in the snake genus Coronella. The small depressions he found in the surface of their scales were considered organs of the sixth sense; Leydig compared them with the taste buds of fishes