The Californias, New Mexico, and the provinces of Sonora, Sinaloa, Chihuahua, Cohuahuila, Durango, Zacatecas, and the northern part of the Anahuac, will now conduct us to the centre of the Aztek civilization--or semi-civilization of the city of Montezuma. And here the enumeration of the divisions and sub-divisions of the population must be almost exclusively geographical, _i.e._ we must take the tribes as they come in their order on the map, and not in the order wherein they are related to each other. The reason of this lies in the unsatisfactory character of our knowledge. Preeminently scanty, it is unsystematic as well. What follows then is but little better than an undigested list of references, more than one of which may refer to the same tribes under different names, and more than one of which may be incorrect. Still it is a contribution towards a monograph, the necessity of which gives it place in a systematic work, which it would not have otherwise; and lest the value of such a monograph, if properly drawn up, be undervalued, the reader is reminded that most of the elements of our criticism in regard to the civilizational phænomena presented by Mexico, Guatimala and Yucatan, depend upon the facts known concerning the Californias and the parts to the south of them. _New California._--_For the parts between the mouths of the rivers Clamet (or Lutuami) and Sacramiento_.--Physical geography gives us for these parts three divisions: _a_, the coast and western boundary of the valley of the Sacramiento; _b_, the valley of the Sacramiento itself; _c_, the eastern watershed of the Sacramiento. _a._ For the coast we have a notice as to the miserable condition of the natives about Trinity Bay in N. L. 41° with the special statement that they file their teeth. Probably they constitute an extension of the Southern Tototunes. On the other hand, the later writers have remarked, that the boundary between the Oregon and California is not only a political but an ethnological one as well; in other words, that the physical appearance of the Indians changes as soon as the frontier is passed. Except so far as there is a difference in the physical geography, this coincidence is unlikely. _b._ In respect, however, to the valley of the Sacramiento, such a difference exists. The Desert of California, like that of the Sahara, has its _oases_, and these are the valleys of its rivers. However narrow these may be, the conditions of physical and social development which they afford, are always improvements upon those of the desert table-land. Here our only data are Mr. Dana's, which consist of-- 1. A vocabulary of the occupants of the river about 250 miles from its mouth, and 60 miles south of the Shasti, whom they resemble, being a mirthful race, with no arms but bows and arrows, and with little intercourse with foreigners.