ME.MOIKS Ul" THE ^'ATI()NAL ACADEMY OE SCIENCES. 173 



sSfi. TllK OKPIIAIJC INDEX. 



The most notable fwUiiro of tliis collectioii of skulls — tlio fciitiiic wliicli iit oiico attracts tlie 

 attention of tlio obsi'ivor — is tlio anti-ro posterior slioiteniiiji. I^xeliidin}^ those whieli bear un 

 doubted evideiu-e of postiuortein distortion, the lon^'cst skull (II. 1,'.!, Table ii) in 48, whose iiulices 

 are obtainable lias ii eephalic index, comi)nted from the measurements pre.scribed by Hroca, of 

 only 7.S.40, which is within the limits of mesatieephaly. There are but 4 skulls which are longer 

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

 index of !»7.!»T. The mean of all tiie IS indices is 88.47, wliicL is an extreme grade of brat-hyce- 

 phaly — the brachystoci'phaly of Huxley. 



i 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 arc of various sizes from those that comprise the entire occipital region, and show 

 definite boundaries to tho.se which might easily escape the attention of the student, or might, dis- 

 as.sociated from the rest of the gioup, be regarded as normal peculiarities. 



The occijtital 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 i)roduced 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 cau^e, 

 uiuler modif^-ing 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 4t5 cases where the occipital depression notably afifects the sagittal circumference we have 

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

 are illustrated in Figs. '20, 27, and 2S, which consist of superimposed outlines adjusted on the 

 bregma, the .superior margin of the meatus anditorius, 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 inion seeming to be little afl'ected, this we may designate as depres- 

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



In the third group (C) the flattening or depres.sion is mostly above the lambda, the median 

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



As the outline.': of all the skulls which satisfactorily illustrate the sagittal depression have 

 been used in coiniiosing Figs. 2(!, 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, Lccien: Olisen'atious on the Crania from the stone graves in Tennessee. Eleventh Annual Report of 

 the Pcabody Museum of Archieology and Ethnology. Cambridge, Mas.s., 1878, pp. 361-384. Shufeldt: A Navajo 

 Skull. Journal olWnatomy and Physiology, A'ol. XX, London, 1885-'86, pp. 426-429. Shikeldt: A Skull of a Navajo 

 Child. .lournal of Anatomy niid Pliysiology, Vol. xxi, London, 1886, pp. 66 el »(■</. Shiikeu>t: Contributions to 

 the Comparative Craniolog\ oltlie North American Indians. Journal of Aiiiitomy and Physiology, Vol. XX I, Lon- 

 don, 18«7, jip. 525 )t scq. M.xso.v. (). T. : Indian Cradles and Head Flattening. Science, Vol. ix, No. 229, New- 

 York, Juno 24, 1897, pp. 617 cl wq. 



