Besides these specified castes there are several others not distinguished by particular names; such, for instance, as the produce of unions between the Mexican Indians or Spaniards and the people of the East Indian continent or Philipines, numbers of whom came over during the old viceroyal government. The best criterion for judging of the purity of blood, is the hair of the women, which is much less deceiving than their complexion. The short woolly hair, or coarse Indian locks, may always be detected on the head or on the back of the neck. This tabular statement exhibits at a glance the mongrel corruptions of the human race in Mexico, and presents an interesting subject for students of physiology and ethnology.[6] CHAPTER III. POPULATION. POPULATION.--CENSUS.--TABLES OF POPULATION.--RELATIVE DIVISION OF RACES.--RELATIVE INTELLECTUAL CULTIVATION.--RELATIVE POPULATION IN HOT AND COLD DISTRICTS. It is to be regretted that no very accurate census of Mexico has ever been made, and that since the year 1831, no effort has been persistently pursued by the government to enumerate its citizens and collect such statistical data as may always be easily gathered by persons engaged in this important task. The irregularity of the central or executive power; the instability of all governments since the establishment of independence; the intestine quarrels, not only in the capital but in the departments or states, have all contributed to, and even partially compelled, this neglect of a great national duty. In the absence, therefore, of official statistics and reports, we are obliged to rely upon approximate results, founded on the _partial_ enumerations of preceding years and the calculations of experienced statesmen and writers. In the following table we shall exhibit all the most trustworthy statements existing either in Mexican works or in the writings of reliable authors:-- VARIANCES BETWEEN THE DIFFERENT CALCULATIONS AND CENSUSES OF THE POPULATION OF MEXICO. Years. No. of Inhabitants.