Among the eight male Munsee sacra in which determination of the number
of segments is feasible, six show five and two show six vertebræ, while
among the 12 female bones there are 10 with five and two with six
segments. We have thus four six-segmented sacra in 20, or 20 per cent.
Emmons, in 217 female Indian pelves, found six segments in 19.8 per
cent of the cases.
Among additional specimens examined by the writer, in 53 sacra of the
southern Utah cliff-dwellers, five vertebræ were present in 37, or 70
per cent; six in 15, or 28 per cent; and seven in one, or 2 per cent.
Of 42 sacra of Southwestern and Mexican Indians, 31, or 74 per cent,
showed five; 10, or 24 per cent, six; and one, or 2 per cent, seven
segments. As to whites, among 503 sacra of miscellaneous Americans
of both sexes, five segments were present in only 66.4 per cent of
the bones; six segments in 31 per cent; seven segments in 2 per cent,
and eight in 0.4 per cent, while the whole coccyx was attached,
non-pathologically, in one instance. The frequency of more than five
vertebræ in the sacrum is therefore slightly to decidedly less in
probably all the tribes of Indians than in the United States whites.