There are certain data available which permit us to estimate rather closely what proportion of the population in California should be regarded as falling within the category of children. Within the missions the annual censuses enable us to compute with accuracy that the individuals under the age of ten years, between the dates 1782 and 1832 averaged 21.4 per cent of the total population (Cook, 1940). This value is relatively high and may not conform to gentile, or aboriginal, conditions. With regard to these we have information from archaeological sources. In the Museum of Anthropology at Berkeley there are several hundred skeletons excavated from habitation sites in central and northern California, the ages of which have been determined and which constitute a fair cross section of the native population during the centuries immediately preceding invasion by the white man. Of these skeletons 22.6 per cent represent persons dying under the age of twenty years, and perhaps 10 or 15 per cent persons dying under the age of ten. Further light is shed by the baptism records of the missions San Jose and Santa Clara (these are discussed in greater detail in a later paragraph) which list gentile baptisms according to village and distinguish between men, women, and children. In the two missions, from approximately 1805 to 1833 there were baptized a total of 5,217 persons from villages in the valley region. Of these 930, or 17.8 per cent were children and 1,939, or 37.1 per cent were listed as men. The sex ratio is 0.826. Evidently the natives captured and brought to the missions do not give us a completely true picture of the composition of the aboriginal population, despite the large sample at our disposal. It is highly probable that (1) the natural sex ratio was nearly unity and (2) many of the men were killed in warfare or escaped the clutches of the convert hunters. Therefore we are justified in setting the number of men equal to that of the women. If we do this, the population represented by the 5,217 conversions was actually 5,626, of which men and women each constituted 41.8 per cent and children 16.4 per cent. Finally, we have figures from Zalvidea (MS, 1806) with respect to villages at the extreme southern end of the San Joaquin Valley. (These are discussed subsequently in connection with the population of that area.) At two of these, after adjusting for disturbed sex ratio, he found respectively 13.5 and 9.6 per cent children. However, Zalvidea's account states specifically that in these villages he carries the age of childhood only through the seventh year. If he had counted as children those under ten years of age, the percentages would naturally have been higher.