The Maya appear to have resorted occasionally to caves as dwelling-places, and certain investigations have been made in caverns at Copan and Loltun (immediately south of Uxmal), in Yucatan. The remains however do not imply that their occupation was of early date, and it is probable that the caves served as places of temporary refuge in times of war. This chapter would be incomplete without some mention of the peculiar bottle-shaped subterranean structures found at certain sites in Yucatan. These are known as “chultunes,” and, since they invariably occur at places remote from rivers, may almost certainly be regarded as cisterns for preserving a supply of water, though in some cases they have served the secondary purpose of burial chambers. They are lined with dressed stone or a coat of stucco, and the mouth is furnished with a stone ring which is closed by a slab. Careful exploration of the chultunes at Labna has been made by Thompson and reported in the “Memoirs” of the Peabody Museum. [Illustration: FIG. 85.--Stone gargoyle, Copan. (_After Gordon_)] It will be unnecessary to enter into a discussion of Maya art, since the subject has been fully treated by Spinden in a monograph which was published only a week or so before this chapter was written, and, moreover, much may be gathered from the preceding pages supplemented by the illustrations. The kinship of the stone reliefs with wood-carving, except at Copan and Quirigua, has already been indicated, and the symbolic nature of Maya ornament is too obvious to need especial mention. Attention may be called to the use of glyphs, extremely ornamental in themselves, to give balance to a design, and to the _horror vacui_ which appears in all reliefs except those of Palenque. Though bound by convention, the result in a large measure of the symbolic nature of his designs, the Maya artist occupies a relatively high plane amongst barbarous peoples. In particular the quality of his line is excellent, even in stone, and in certain respects, notably foreshortening (especially in the treatment of feathers, for which see Figs. 61 and 87; pp. 297 and 367), he was superior to the sculptor of Egypt or Assyria. One peculiarity of Maya art lies in the fact that the artist was obsessed by the motive of the serpent (rattle-snake) head. In nearly all its essentials this design appears in the remarkable gargoyle from Copan shown in Fig. 85. We have here the exaggerated upper jaw, the front fang, and the curl at the corner of the mouth. One detail is lacking, viz. the nose-ornaments which were usually added to the reptile. Maudslay has shown how derivatives of this design, often modified almost beyond identification, are constantly applied to every form of ornament, such as the edges of girdle-flaps and so forth, and the point has been elaborated by Spinden. Most interesting is the almost invariable occurrence of the serpent-motive on the wings of birds (e.g. Figs. 48 and 49; pp.