Sentence:  The <WSD>moieties</WSD> are linked to or bear the names of beings or forces expressing the cosmic dichotomy. Most common are heaven and earth <WSD>moieties</WSD>, "above" and "below," or <WSD>moieties</WSD> named after birds and land animals (or aquatic animals), as is the case among the Winnebago and in the phratry system of the Northwest Coast Indians. 
Meaning of the word marked with <WSD> tags:  Each descent group in a culture which is divided exactly into two descent groups.