In Mr. Morgan’s work on _Primitive Society_, published in 1871, are to be found the systems of consanguinity and affinity of 139 tribes and races representing, numerically, four-fifths of the entire human family. These systems show conclusively that the restrictions on marriage observed in the gens did not extend to the tribe. The author of _Primitive Marriage_ has evidently mistaken a rule of the gens for a binding tribal decree. Mr. McLennan’s theory relative to female infanticide is found to be equally fallacious. Noting the numerical difference in the two sexes among lower races, he says that as subsistence was scarce, and as war was the natural and constant condition of primitive groups, only those of their members would be spared who could contribute to the defence of the tribe, or who would be able to aid in the supply of subsistence. Males were possessed of strength, they were by organization and inclination adapted to war and the chase, and could therefore be depended upon to assist in defending the tribe against the assaults of its enemies and in securing the necessary food for its requirements. On the other hand, women being worthless in war and in the chase were regarded as useless appendages, and as they constituted a source of weakness to the tribe, large numbers of them were destroyed at birth. Through this practice the balance of the sexes was greatly disturbed, and wives could be obtained only by means of stealth or a resort to force. Thus in process of time, the stealing of women became a legitimate practice, and each warrior depended on his skill in this particular direction to provide himself with a wife. Finally the children of these alien women began to intermarry and thus the necessity for wife-capture no longer existed, and the practice of stealing women for wives was superseded by a system through which wives from other tribes were habitually obtained either by gift or sale. Thereafter the symbol of wife-capture was retained in marriage ceremonies. With a better understanding of peoples in a less developed state of society, it is found that infanticide has been less prevalent among them than was formerly supposed; that when through scarcity of food it has been practised it has not been confined to females, neither has it been carried on by tribes in the lowest stages of barbarism. Regarding this custom in Arabia, Prof. W. R. Smith says that our authorities “seem to represent the practice of infanticide as having taken a new development not very long before the time of Mohammed.” This writer declares that the chief motive for infanticide was “scarcity of food which must always have been felt in the desert.”