The best discussed and probably the most interesting of the petroglyphs in the region are described and illustrated by Mr. W. H. Holmes (_a_), of the Bureau of Ethnology. The illustrations are here reproduced in Figs. 34 to 37, and the remarks of Mr. Holmes, slightly condensed, are as follows: The forms reproduced in Fig. 34 occur on the Rio Mancos, near the group of cliff houses. They are chipped into the rock evidently by some very hard implement and rudely represent the human figure. They are certainly not attempts to represent nature, but have the appearance rather of arbitrary forms, designed to symbolize some imaginary being. [Illustration: FIG. 34.--Petroglyphs on the Rio Mancos, Colorado.] The forms shown in Fig. 35 were found in the same locality, not engraved, but painted in red and white clay upon the smooth rocks. These were certainly done by the cliff-builders, and probably while the houses were in process of construction, since the material used is identical with the plaster of the houses. The sketches and notes were made by Mr. Brandegee. The reproduction is approximately one-twelfth the size of the original. [Illustration: FIG. 35.--Petroglyphs on the Rio Mancos, Colorado.] The examples shown in Fig. 36 occur on the Rio San Juan about 10 miles below the mouth of the Rio La Plata and are actually in New Mexico. A low line of bluffs, composed of light-colored massive sandstones that break down in great smooth-faced blocks, rises from the river level and sweeps around toward the north. Each of these great blocks has offered a very tempting tablet to the graver of the primitive artist, and many of them contain curious and interesting inscriptions. Drawings were made of such of these as the limited time at my disposal would permit. They are all engraved or cut into the face of the rock, and the whole body of each figure has generally been chipped out, frequently to the depth of one-fourth or one-half of an inch. [Illustration: FIG. 36.--Petroglyphs on the Rio San Juan, New Mexico.] The work on some of the larger groups has been one of immense labor, and must owe its completion to strong and enduring motives. With a very few exceptions the engraving bears undoubted evidence of age. Such new figures as occur are quite easily distinguished both by the freshness of the chipped surfaces and by the designs themselves. The curious designs given in the final group have a very perceptible resemblance to many of the figures used in the embellishment of pottery.