220 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



more frequently and forcibly extended tlian the right. For the majority of human manual tasks 

 we are not prepared to demonstrate this, although we might do so in some instances. In the work 

 of grinding on the nictate, however, it appears tliat the left hand is used the more. When the 

 grist is lifted from the trough and placed on the metate — and this is very frequently done — the 

 right hand is employed while the left hand is not released from the grinding- stone. 



$ 32. THE PELVIS. 



Pelvic measurements have been practiced upon 19 articulated pelves besides one pair of 

 innominate bones, 2 innominate bones of separate individuals with their corresponding sacra, 1 

 without sacrum, and 8 separate sacra (Tables lxi to Lxviii, inclusive). 



The measurements are as accurate as could be hoped for in pelvimetry where landmarks are 

 relatively quite indistinct. 



No measurement has been permitted to originate with us. The series of 19 measurements 

 are compiled from Garson* and Verneau.+ Fritsch,^ Davis,§ and Bacarisse,|| have also been con- 

 sulted and the choice of each measurement determined by its frequency in use and its clear defini- 

 tion fully as much as by its apparent morphological utility. It was our orginal intention to ex- 

 tend the number of measurements to 21 by including a measurement of the height of the entire 

 articulated pelvis and the subpubic angle; but although both these measurements have often 

 been taken by investigators, we could not find sufdciently exact definitions to warrant our adoption 

 of them. 



The indices which have been calculated by different authors are very varied. In view of this 

 fact, and also because all published series of measurements which we have examined deal with 

 series which compared to craniological series are absurdly small, we have limited our indices to the 

 two which Topiuard especially recommends,^ and a few others which appear most useful in the 

 discrimination of sex. 



Verneau, however, seems to base his discussion of sex on anatomical differences and absolute 

 measurements, while J. G. Garson and most other writers have given us practically no informa- 

 tion concerning the male pelvis. Hence as we are dealing with an unknown people, indeed almost 

 all American tribes are unknown to pelvimetricians, and a people of probably conspicuously small 

 stature, we might very readily go astray in applying to any great extent the canons or results of 

 European anthropometry. 



With these cousiderations in view we have decided upon the following indices : 



First. — The breadth-height index or relation of the maximum external width of the pelvis at 

 the iliac crest to its maximum height, or, which is the same thing, the maximum length of the in- 

 nominate bone. 



Pelvic height. 

 Second. — Index of the superior strait. 



^ , Antero-posterior diameter of brim x 100 



l*ormula: =^ -^ jr^—, 



Transverse diameter ot brim. 



Third. — Index of the pubo-ischiatic depth. 



Formula- P ubo-ischiatic depth x 100 



Maximum width of superior strait. 



Fourth. — Index of sacral length. 



Formula: . SacrallengthxlOO 



Maximum width ot superior strait. 



" Garson : Pelvimetry ; Journal of Anatomy and Physiology, London, 1881-'82 ; pp. 106 et seq. 

 t Verneau : Le Bassin ; Paris, 1875. 



t Fritsch : Die Eingeborenen SUd-Afrika's, Breslau, 1872, Tabelle ii. 

 § Davis : Thesaurus Cranioruin, London, 1867, Appendix B. 

 II Bacarisse : Du Sacrum, Paris, 1873 ; Thfese pour le doctorat. 

 H ToPLNARD : jjldments d' Authropologie G6n6rale, Paris, 1885. p. 1049. 



