The head-variant numerals are shown in figures 51-53. Taking these up in their numerical order, let us commence with the head signifying 1; see figure 51, _a-e_. The essential element of this head is its forehead ornament, which, to signify the number 1, must be composed of more than one part (), in order to distinguish it from the forehead ornament (), which, as we shall see presently, is the essential element of the head for 8 (fig. 52, _a-f_). Except for their forehead ornaments the heads for 1 and 8 are almost identical, and great care must be exercised in order to avoid mistaking one for the other. {98} The head for 2 (fig. 51, _f_, _g_) has been found only twice in the inscriptions--on Lintel 2 at Piedras Negras and on the tablet in the Temple of the Initial Series at Holactun. The oval at the top of the head seems to be the only element these two forms have in common, and the writer therefore accepts this element as the essential characteristic of the head for 2, admitting at the same time that the evidence is insufficient. [Illustration: FIG. 52. Head-variant numerals 8 to 13, inclusive.] The head for 3 is shown in figure 51, _h_, _i_. Its determining characteristic is the fillet, or headdress. The head for 4 is shown in figure 51, _j-m_. It is to be distinguished by its large prominent eye and square irid (). (probably eroded in _l_), the snaglike front tooth, and the curling fang protruding from the back part of the mouth () (wanting in _l_ and _m_). {99} The head for 5 (fig. 51, _n-s_) is always to be identified by its peculiar headdress (), which is the normal form of the tun sign. Compare figure 29, _a_, b. The same element appears also in the head for 15 (see fig. 53, _b-e_). The head for 5 is one of the most constant of all the head numerals. [Illustration: FIG. 53. Head-variant numerals 14 to 19, inclusive, and 0.] The head for 6 (fig. 51, _t-v_) is similarly unmistakable. It is always characterized by the so-called hatchet eye (), which appears also in the head for 16 (fig. 53, _f-i_). The head for 7 (fig. 51, _w_) is found only once in the inscriptions--on the east side of Stela D at Quirigua. Its essential characteristic, {100} the large ornamental scroll passing under the eye and curling up in front of the forehead (), is better seen in the head for 17 (fig. 53, _j-m_).