A STUDY OF THE VARIATIONS IN THE FEMALE PELVIS, 
BASED ON OBSERVATIONS MADE ON 217 SPECIMENS 
OF THE AMERICAN INDIAN SQUAW*. 
By ARTHUR BREWSTER EMMONS, A.B., M.D. (Harvard), Boston, 
Mass., U.S.A. 
The object of this investigation was to determine, so far as possible, the 
variation in form of the " normal " human female pelvis. By " normal " it was 
intended to exclude all pathological pelves, and to include all variations, not the 
results of disease. Our conception of " normal," for a standard of comparison, 
should, I believe, include not only the average measurements, but also the 
minimum and maximum as well as the proportion of cases at regular intervals 
between these extremes. 
The bones of the American Indian of the earlier times, collected from various 
parts of North and South America and the adjacent islands, are said by the 
authorities on the Indian (1) to be entirely free from rhachitis, and that other 
diseases affecting the bones, as tuberculosis, osteomalacia, and syphilis, are rare. 
This statement was borne out in my series of specimens, for no evidence of these 
diseases was encountered. In an occasionally elderly specimen, however, the 
remains of an old osteo-arthritic process were found. This late change could 
have had little or no effect on the form of the pelves. 
Varying conditions, exclusive of disease, such as differences of nutrition, and 
certain habits as sitting up for long periods in early infancy, carrying heavy 
burdens in youth, are the common causes and most probable influences modifying 
the shape of tlie pelvis. Among the many Indian tribes from which the specimens 
of this series came, these factors may have been present at times in varying 
degrees, yet it seems fair to consider them all as from a pure unmixed race, and 
thus the series should yield a true type. 
A due proportion of variations can scarcely be obtained with certainty unless 
at least 200 specimens are used. A still larger series than mine might yield 
* Awarded the Boylston Medical Prize Essay, 1912. " The Boylston Medical Committee do not 
consider themselves as approving the doctrines contained in any of the dissertations to which premiums 
may be adjudged." 
