The mammalian fossils, numbering approximately 150 specimens, were all obtained within a small area located in the NW 1/4 of sec. 14, T. 27 N, R. 11 W, San Juan County, New Mexico. The specimens were collected from a zone of reddish silt three to four feet in thickness. The actual bone layer, not as yet located, may prove to be thinner than this. Almost all the material was recovered from approximately 100 linear yards of outcrop. A few specimens, however, were obtained at varying distances away from this central area, as far distant perhaps as one-half mile. Of these, nineteen were at the same level stratigraphically, and only one was lower (by 70 feet) in the section. This latter specimen, representing a new genus and species of Primates, is not certainly duplicated by material at the main concentration. Seemingly, the others are.

The red zone at the "bone pocket" carries many concretionary masses which frequently contain the fossil specimens. Not all specimens, however, are from such lumps.

Even within the area of greatest concentration, specimens are of sporadic occurrence. A low ridge, a few feet high, may have abundant material weathering from the rock on one slope, but have the opposite side barren. Occasionally, a small rill three or four feet in length and six inches or so across may carry fragments of five or six individuals representing several genera. For example, in one such rill were found Didymictis, n. sp. b; Goniacodon levisanus; Tricentes cf. T. subtrigonus; and Protoselene opisthacus. No specimens were found in place in unweathered rock, but the quarry possibilities of the bone pocket have still to be tested.

The stratigraphic position of the bone concentration in relation to the total Nacimiento section exposed in Kutz Canyon has not been determined. It is approximately 160 feet below the western rim at a point nearest the "pocket". The upper 100 feet of strata consists of sandstone believed by Granger (1917:822) to represent either: (1) equivalent of the "Wasatch" (San JosÉ) of the Ojo Alamo section, or (2) "Torrejon" (upper Nacimiento). Granger perhaps favored the first interpretation, but the writer, at present, thinks the second probable.