i found a better reference in page theoretically polygamy can assume any one of three possible forms polygyny or the marriage of one man to two or more wives at a time polyandry or the coexistent union of one woman with two or more men and group marriage or a marital union embracing at once several men and several women of these only the first is common and on page a statistical analysis of kaingang genealogies for a period of years showed that per cent of all recorded unions were group marriages as compared with per cent for polyandrous per cent for polygynous and per cent for monogamous unions the disadvantage of working at a medical school is that the anthropology texts are not extensive but they aren't checked out often either this had been sitting on the shelf for over years deep in the recesses of the basement murdock is a sufficient reference for polygamy including group marriage