Linear distances along streams are useful as a basis for comparison in country where the rivers are similar ecologically but are clearly separated spatially and where the human population is concentrated along the stream banks to the exclusion of the interfluvial hinterland. Where a territory is marked by a network of creeks and sloughs, and the intermediate land is marsh, the linear comparisons become impossible. Areas must be substituted. In relation to the present problem three such areas may be delineated. The first comprises the territory of the Bolbones (including all the subordinate villages) and the Leuchas. Following Schenck's map, it embraces all the land between the channels of the San Joaquin plus a strip approximately two miles wide east of the main river in T1 and 2S, R6E which accounts for the Leuchas. The area, as projected from a large-scale map onto coördinate paper, is 775 square miles, the population 3,400, and the density 4.39 persons per square mile. The second comprises the home of the Ochejamnes, Guaypem, Quenemsias, and Chucumnes-Chuppumne. For the habitat of these groups we have followed Schenck as far as possible. Our line runs actually from the junction of the east and west channels of the Sacramento at the foot of Grand Island southeast to the main channel of the San Joaquin, thence northeast and north to just east of Walnut Grove and then, at a distance of about 2 miles east of the eastern channel of the Sacramento, to a point 4 miles north of Courtland. Here the line crosses the river and continues downstream, 2 miles west of the river, to the starting point. This strip of the western bank of the western branch of the Sacramento is included in order to take in the Chucumes, who may have lived on the west side of the river. The area of this territory is 330 square miles, the population 2,950, and the density 8.94 persons per square mile. The third area is the one shown by Schenck as belonging to the Chupunes, Tarquines, Julpunes, and Ompines, with the exception of the region east of the San Joaquin attributed to the Tarquines. For reasons stated previously the author does not believe that the Tarquines occupied this spot aboriginally. A strip 2 miles wide is included on the north shore, however, between Rio Vista and Collinsville, in the probable land of the Ompines. The eastern boundary is formed by the borders of areas one and two. In area three there are 600 square miles. The mean of the densities of the other two areas is 6.67 persons per square mile. Hence the population would have been 4,002 persons. No significance should be attributed to the third and probably also the second digit in these numbers. They are used only for purposes of estimate. The three methods employed have yielded respectively 3,000, 2,000, and 4,000 as the most likely population of the five groups here being discussed. In default of any other evidence we may take the average 3,000.