Page:Natural History, Reptiles.djvu/93

Rh entirely bony in its back part, nor has it, so to speak, any flooring; so that when deprived of the softer parts, the cavity communicates with the mouth. The articulation of the jaw is quite backward." The spinal column is destitute of any bony processes or projections; the vertebræ are said to be hollowed out, on their anterior and posterior surfaces, into conical cavities, somewhat like the vertebræ of fishes. The number of ribs varies according to the species.

We have said that the skin is easily detached; when held up to the light, it is seen to be regularly furnished with small, delicate, rounded, escutcheon-like bodies, set in its substance. The form and distribution of these bodies are different in different species, and they are found in the skin of the belly, the neck, the head, the thighs, and the tail.

The colours of the Geckos are commonly sombre, and even lurid; frequently various shades of grey and brown, more or less irregularly clouded or mottled; they have the power in some degree of changing their hues, the colours being darker or paler, and the markings becoming visible or evanescent, at will. Some of the small species are marked with bright colours, which are not mutable. Wagler was informed by some travellers, that certain Geckotidæ of India become luminous or phosphorescent during the night; but we know not how far this information is to be depended on. The skin is moulted or sloughed off, at certain times, when that which envelops the head and fore partsforeparts [sic] of the body is detached first, the separation proceeding gradually to