Sentence:  The villages are divided into two patrilineal totemic <WSD>moieties</WSD> and two patrilineal ceremonial <WSD>moieties</WSD>. The totemic <WSD>moieties</WSD> are subdivided into patrilineal clans ("ngaiva"): there are between fifty and a hundred clans of which between ten or twenty are represented in any one villagenb.... 
Meaning of the word marked with <WSD> tags:  Each descent group in a culture which is divided exactly into two descent groups.