The prevalence of horizontal and the rarity of vertical symmetry is presumably due to the absence of vertically symmetrical movements,—except in those rhythmic movements in which the arms are alternately raised and lowered,—and in the rarity of natural forms that are vertically symmetrical. In nature we see generally more fundamental differences in vertical direction than in horizontal layers. In animals, legs, body and head are on different levels. In landscapes, earth, trees, mountains and sky follow one another in vertical succession. On the other hand, we are liable to find in horizontal sequence sameness or variations of analogous form. This may be one of the reasons why there are found in ornamental art frequent arrangements in a series of horizontal bands that differ fundamentally in pattern, while in each horizontal band we find either symmetry, rhythmic repetition, or variations of similar forms (figs. 24, 25, 26). Exceptions however, occur, for instance in the decorations of Melanesian houses (Plate III). Other causes may contribute to the development of symmetrical patterns. In the making of coiled pottery or coiled basketry symmetry results from the process of manufacture. By regular turning of the pot or basket a circular form is produced. The process of winding twine around a holder may have the same effect. In two-handed implements, such as the bow of the bowdrill, symmetrical forms also develop, but implements of this type are not by any means numerous and their occurrence is no adequate explanation of the general occurrence of symmetry. We must leave it undecided whether the circumstances here referred to are adequate to account for the symmetry of form of such implements as lance heads, arrow-heads, baskets and boxes. We must be satisfied with the establishment of their general occurrence and the knowledge that they have an esthetic value wherever they are found. Examples of symmetrical arrangements are very numerous. The boxes from British Columbia (fig. 274, p. 263), neckrests of the Kaffers (fig. 9, p. 23), Melanesian shields and paddles (fig. 10, p. 25), and the painted rawhides of the Sauk and Fox (figs. 13-15, pp. 27, 28) may serve as exemples. A special type of symmetrical design is found in our heraldic style with its animals rampant on each side of a central field. It is interesting to note that the same arrangement is very ancient. It occurs on the Lions’ Gate of Mycenae. It has also developed independently in prehistoric Peru (fig. 27). [Illustration: PLATE III. Decorated House, Northern New Guinea.] [Illustration: Fig. 24. Patterns from bamboo combs, Malay Peninsula.] [Illustration: Fig. 25. Design from bamboo spear, New Guinea.] [Illustration: Fig. 26. Etruscan vase.] [Illustration: Fig. 27. Peruvian designs.]