The duties incidental to clan membership are the following: The obligation not to marry within the clan, formerly not even within the sisterhood or phratry of clans, to which the one in question belonged; the effect of membership in the sisterhood of clans was to make all men either mother’s brothers or brothers, and all women mothers or sisters. (2) The joint obligation to purchase the life of a member of the clan which has been forfeited by homicide or the murder of a member of the tribe or of an allied tribe. (3) The duty and obligation to aid and to defend its members in supplying their wants, redressing their wrongs and injuries through diplomacy or by force of arms, and in avenging their death. (4) The joint obligation to replace with prisoners or other persons other members who have been lost or killed, belonging to any ohwachira of a clan to which they may be related as father’s brothers or father’s clansmen, the matron of such ohwachira having the right to ask that this obligation be fulfilled. The clan name is not usually among the Iroquois the common designation of the animal or bird or reptile after which the clan may be called, but very commonly denotes some marked feature or characteristic or the favorite haunt of it, or it may be just a survival of an archaic name of it. The number of clans in the different Iroquois tribes varies; the smallest number is three representative clans, found in the Mohawk and the Oneida, while the Seneca have nine and the Onondaga eight. There are also some clans which, having no chief titles, are seldom named in public. In historical times, and in the past as far as tradition informs us, every clan belonged to a sisterhood or phratry of clans, and so was not directly a member of a tribe. In all Iroquois tribes two sisterhoods or phratries of clans are found, each forming one side of the dual tribal organization. One of the tribal sides represents the fatherhood or male principle and the other the motherhood or female principle among living things.