The cutis of most Amphibia is very rich in lymph-spaces, which, especially in the Anura, assume enormous proportions, since the so-called subcutaneous connective tissue forms {34}comparatively few vertical septa by which the upper and denser layers, the corium proper, are connected with the underlying muscles. The spaces are filled with lymph, and into some of them the abnormally expanded vocal sacs extend, notably in _Paludicola_, _Leptodactylus_, and other Cystignathidae, and in _Rhinoderma_. The cutis frequently forms papillae and prominent folds, sometimes regular longitudinal keels on the sides of the back; but dermal, more or less calcified or ossified scales are restricted to the Stegocephali and to the Apoda, _q.v._, pp. 79, 87. We conclude that the Urodela and Anura have entirely lost these organs. Dermal ossifications, besides those which now form an integral part of the skeleton, like many of the cranial membrane-bones, are rare, and are restricted to the Anura. They are least infrequent on the head, where the skin is more or less involved in the ossification of the underlying membrane-bones, for instance in _Triprion_, _Calyptocephalus_, _Hemiphractus_ and _Pelobates_. The thick ossifications in the skin of the back of several species of _Ceratophrys_ are very exceptional. In _Brachycephalus ephippium_ these dermal bones enter into connection with the vertebrae; small plates fuse with the dorsal processes of the first to third vertebrae, while one large and thick plate fuses with the rest of the dorsal vertebrae. Simple calcareous deposits in the cutis are less uncommon, for instance, in old specimens of _Bufo vulgaris_. We are scarcely justified in looking upon these various calcifications and even ossifications as reminiscences of Stegocephalous conditions. The skin contains PIGMENT. This is either diffuse or granular. Diffuse pigment, mostly dark brown or yellow, occurs frequently in the epidermis, even in the stratum corneum. The granular pigment is stored up in cells, the chromatophores, which send out amœboid processes, and are restricted to the cutis, mostly to its upper stratum, where they make their first appearance. Contraction of the chromatophores withdraws the pigment from the surface, expansion distributes it more or less equally. The usual colours of the pigment are black, brown, yellow, and red. Green and blue are merely subjective colours, due to interference. A peculiar kind of colouring matter is the white pigment, which probably consists of guanine, and is likewise deposited within cells; cf. the description of the white spots in the skin of _Hyla coerulea_. {35}Most Amphibia are capable of changing colour, the Urodela, however, far less than the Anura, some of which exhibit an extraordinary range and adaptability in their changes.