. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 20 COMPARATIVE ANATOMY as the colour becomes modified according to the surroundings of the animal, it may serve as a protection [ Hyial. Calcifications may occur in the dermis, or as m Ceratophrys dorsata, definite lones may be formed (see p. 33) : the dermis also encloses numerous smooth muscle-fibres. Reptilia.—The characteristic peculiarity of the skin of Reptiles is its capacity of producing scales (these are very simple m Geckos and Chameleons), warts, pricldcs, shields { the " tortoiseshell_ of Chelo
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 20 COMPARATIVE ANATOMY as the colour becomes modified according to the surroundings of the animal, it may serve as a protection [ Hyial. Calcifications may occur in the dermis, or as m Ceratophrys dorsata, definite lones may be formed (see p. 33) : the dermis also encloses numerous smooth muscle-fibres. Reptilia.—The characteristic peculiarity of the skin of Reptiles is its capacity of producing scales (these are very simple m Geckos and Chameleons), warts, pricldcs, shields { the " tortoiseshell_ of Chelonians), elaios, rattles (Rattlesnake), and other epidermic structures (Fig. 13). All these are due in the first instance to the formation of dermal papillae, the markedly stratified epidermis coverino- which becomes coraified secondarily. The horny layer ot the epidermis may be periodically cast off either entire (Snakes) B -h Tmpr^^^^^^^^WM-. Fig. 13.— Seotioxs Through Various Rinds of Epidermic Scales or Reptiles. (From Boas's Zoology.) I, rounded scales ; B, shields ; C, imbricating scales ; X*, overlapping scales with bony scutes in the underlying dermis; h, horny layer; «, Malpighian layer of the epidermis ; 1, dermis ; o, bony scutes. or in shreds: it is renewed from the Malpighian layer. The integument of Hatteria retains the most primitive characters amongst Reptiles. Pigment-cells occur in the integument, rendering a change of colour possible in many cases { Chameleon). Ossifications in the dermis are very common in Reptiles, and there is great variation in the degree of their development, from the small bony scutes present in Geckos (Ascalabota) to the large exoskeletal plates of Chelonians (see p. 33). Muscles are also present in the dermis. In contrast to the skin of Amphibians, that of Reptiles is entirely wanting in glands. In Lizards, tlie so-called femoral glands occurring along the ventral side of the thigh are said to be merely solid cone
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
