MEMOIBS OF THE NATIONAL ACADEMY OF SCIENCES. 173 



$ 6. THE CEPHALIC INDEX. 



The most notable feature of this collection of skulls the feature which at once attracts the 

 attention of the observer is the antero-posterior shortening. Excluding those which bear un 

 doubted evidence of post-mortem distortion, the longest skull (H. 23, Table n) in 48, whose indices 

 are obtainable has a cephalic index, computed from the measurements prescribed by Eroca, of 

 only 78.40, which is within the limits of mesaticephaly. There are but 4 skulls which are longer 

 than sub-brachycephalic, and but 7 which are not truly brachycephalic. The shortest skull has an 

 index of 97.97. The mean of all the 48 indices is 88.47, which is an extreme grade of brachyce- 

 phaly the brachystocephaly of Huxley. 



$ 7. OCCIPITAL FLATTENING. 



Associated with this shortening of the skull we find more or less depression or absolute flat 

 tening of the occiput. In the most marked cases we can not doubt that this flattening is artifi 

 cially, although not necessarily intentionally, produced. Between the very flat occiputs and those 

 which, though not prominent, are quite rounded there are many degrees of variation and the areas 

 of the flattening are of various sizes from those that comprise the entire occipital region, and show 

 definite boundaries to those which might easily escape the attention of the student, or might, dis 

 associated from the rest of the group, be regarded as normal peculiarities. 



The occipital flattening here referred to, must be carefully distinguished from that produced 

 intentionally by the ancient Peruvians, by the Flatheads of our Northwest coast, and by other 

 races. In the latter there is an anterior counter-flattening produced by the pressure applied to the 

 forehead; in the former there is no frontal flattening. 



The cause of this flattening of the occiput, whatever it may be, would seem to be the cause, 

 under modifying circumstances, of the brachycephaly in general, whether absolute flattening 

 exists or not. Such flattening has been observed among various American races, both extinct and 

 extant, and is by some attributed to the use of a hard board for the back of the basket, case, or 

 cradle in which the baby is carried.* There is no doubt in our mind that this is the prime cause 

 of the flattening and the brachycephaly in the skulls of this series. The variations may depend 

 on the different degrees of hardness of the skulls or on the character and size of the pad or pillow 

 used, or on both. 



In 46 cases where the occipital depression notably affects the sagittal circumference we have 

 it variously distributed. This distribution may be broadly divided into three groups. These 

 are illustrated in Figs. 26, 27, and 28, which consist of superimposed outlines adjusted on the 

 bregma, the superior margin of the meatus auditorius, and German horizontal plane. 



In the first group (A) the depression, whether there is actual flattening or not, is pretty 

 evenly distributed over the entire posterior portion of the sagittal curve from the opisthion to the 

 obelion. This may be called total posterior depression. (See Fig. 26.) 



In the second group (B) the depression is mostly from the inion to the obelion ; that portion 

 of the median line below the iiiion seeming to be little affected, this we may designate as depres 

 sion above the inion. (See Fig. 27.) 



In the third group (C) the flattening or depression is mostly above the lambda, the median 

 line below that point being nearly or quite normal. (See Fig. 28.) 



As the outlines of all the skulls which satisfactorily illustrate the sagittal depression have 

 been used in composing Figs. 26, 27, and 28, it will be seen that the first group is much the most 

 numerous, there being 14 skulls of this group to 6 of the second and 4 of the third. 



* CARR, LUCIEN: Observations on this Crania from the stone graves in Tennessee. Eleventh Annual Report of 

 the Pcahod. - Museum of Aivlurology and Ethnology. Cambridge, Mass., 1878, pp. 361-384. SHUFKU&amp;gt;T: A Navajo 



Skull. J mil i&amp;gt; ! . \ii:itn my and Physiology , Vol. XX, London, 1885- 86, pp. 426-429. SurKKLDT: A Skull of aXavajo 



Child. .Journal of Anatomy and Physiology. Vol. xxi, London, 1886, pp. 66 el m/. Surri-.i.ni : Contributions to 

 thr ( omparat i\ c Ci-:iniolc&amp;gt;^\ oi t lie. North Anicnr;iii Indians. Journal of Anatomy and Physiology, Vol. \\i. Lon 

 don, 18X7, pp. &quot;&amp;gt; - &amp;lt;t si q. MASON, it. T. : Indian ( radios and Head Flattening. Science, Vol. ix, No. 22!l. \c\\ 

 York, June 24, 1897, pp. 617 el /. 



