The materials upon which the Maya glyphs are presented are stone, wood, stucco, bone, shell, metal, plaster, pottery, and fiber-paper; the first-mentioned, however, occurs more frequently than all of the others combined. Texts have been found carved on the wooden lintels of Tikal, molded in the stucco reliefs of Palenque, scratched on shells from Copan and Belize, etched on a bone from Wild Cane Key, British Honduras, engraved on metal from Chichen Itza, drawn on the plaster-covered walls of Kabah, Chichen Itza, and Uxmal, and painted in fiber-paper books. All of these, however, with the exception of the first and the last (the inscriptions on stone and the fiber-paper books or codices) just mentioned, occur so rarely that they may be dismissed from present consideration. The stones bearing inscriptions are found in a variety of shapes, the commonest being the monolithic shafts or slabs known as _stelæ_. Some of the shaft-stelæ attain a height of twenty-six feet (above ground); these are not unlike roughly squared obelisks, with human figures carved on the obverse and the reverse, and glyphs on the other faces. Slab-stelæ, on the other hand, are shorter and most of them bear inscriptions only on the reverse. Frequently associated with these stelæ are smaller monoliths known as "altars," which vary greatly in size, shape, and decoration, some bearing glyphs and others being without them. The foregoing monuments, however, by no means exhaust the list of stone objects that bear hieroglyphs. As an adjunct to architecture inscriptions occur on wall-slabs at Palenque, on lintels at Yaxchilan and Piedras Negras, on steps and stairways at Copan, and on piers and architraves at Holactun; and these do not include the great number of smaller pieces, as inscribed jades and the like. Most of the glyphs in the inscriptions are square in outline except for rounded corners (fig. 9, _c_). Those in the codices, on the other hand, approximate more nearly in form rhomboids or even ovals (fig. 9, _a_, _b_). This difference in outline, however, is only superficial in significance and involves no corresponding difference in meaning between {23} otherwise identical glyphs; it is due entirely to the mechanical dissimilarity of the two materials. Disregarding this consideration as unessential, we may say that the glyphs in both the inscriptions and the codices belong to one and the same system of writing, and if it were possible to read either, the other could no longer withhold its meaning from us.