The following pages have a twofold purpose. First, there is extended to new territory an analysis of aboriginal population and ecology in California which has already encompassed the San Joaquin Valley (Cook, 1955) and the north coast (Cook, 1956). The area treated here is a portion of that occupied by the Costanoan linguistic division, which extended from San Francisco Bay throughout the interior ranges and along the coast as far south as the latitude of Salinas and Monterey. However, in view of the many accounts which have been written concerning the settlement of coastal California and the establishment of the missions, it seems preferable to devote attention almost exclusively to one restricted region and to deal with this as exhaustively as possible. The area selected embraces the east shore of San Francisco Bay and its hinterland, including what is now Alameda and Contra Costa counties. It is quite true that some of the tribal groups inhabiting this territory may not have been members of the Costanoan stock. On the other hand, in their relation both to the native environment and to the invading white man their activity conformed in all important ways to that of their bona fide Costanoan neighbors. Hence it is proper to treat all the aborigines in the area on a common basis.

Second, emphasis has been placed upon setting forth in detail sources of knowledge. There are a number of documents describing conditions in the East Bay from 1770 to 1820. Certain of these, such as the Crespi-Fages and the Font-Anza diaries, have been made available in excellent translations, particularly by Herbert E. Bolton, and although they must be examined and analyzed with care, only a few passages need to be reproduced verbatim. Other documents, some of them of considerable general interest, are almost unknown, not only to students of ethnography, but also to many others concerned with preconquest and early colonial California. Among these may be mentioned the CaÑizares exploration of San Francisco Bay, and the diaries of Father Danti and Sergeant Amador. Therefore, although a good deal of the material contained in these documents does not bear directly upon either population or ecology, it seems to me worth while to translate and reproduce them in full. Their intrinsic interest is adequate compensation for the moderate amount of extra space consumed.