230 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



■whose highest index is 97.97. We have seen record of but few indices higher than the above of 

 100.G9. The average cephalic index of this group (88.80) is higher than that of the Saladoans by 

 a small fraction, notwithstanding that there are 5 Cibolau skulls longer than the longest Saladoan. 



The minimum index, 74. 54, which is dolichocephalic according to some authorities, belongs to 

 a skull apparently normal and possibly of an alien race. 



The supposed reasons for this shortening have already been declared. 



$ 37. OCCIPITAL FLATTENING. CIBOLA. 



This deformation, whatever be its significance, is the rule in the collection under consideration. 

 Only 4 skulls, indeed, Nos. H. 201, H. 204, H. 221, and H. 229, can be called normal in outline. 



Of the deformity of the reinaining skulls it may be said that it can be most impressively 

 explained by imagining it to have been made by a flat rigid surface moving in a plane vertical or 

 tilted a little forward with reference to the antero postero-horizontal plane of the skull, coming in 

 contact with the occiput. Hence we find the flattening in the less notable cases involving only 

 the most prominent part of the occiput, that is, from inion to lambda. Then we find a number 

 flattened from inion to obelion, and lastly a few in which the whole occiput is affected. But this 

 plane, while always approximately vertical to the aforesaid horizontal plane, may be either parallel 

 to or at any angle with the transverso-vertical plane of the skull. 



Hence the flattening may be strictly unilateral; or the flattening may affect both sides, but 

 preponderate upon one; or the flattening may be bilaterally symmetrical. There are 10 skulls 

 in which the flattening is nearly or quite bilaterally symmetrical. Eight skulls are flattened on 

 the left side of the occiput, and twelve skulls are flattened on the right side of the occiijut. 



There is no skull exemplifying that occipital flattening wherein the occiput seems to have been 

 in contact with a force pressing upward and forward. The resultant form is one in which the 

 obelion is, or tends to be, the most posterior part of the skull, while the surface from the lambda 

 to the inferior ciu'ved line, or even to the opisthion, forms a nearly continuous plane. 



^ 38. VERTICO-LONGITUDINAL INDEX. CIBOLA. 



The general remarks under the title " Vertical indices" (§ 11) made on the Saladoan skulls 

 apply as well to the Cibolan, although we have placed on record for the latter only one vertical 

 index, the A'ertico-longitudinal, whose factors are the greatest length and the basi-bregmatic 

 height. (See Tables lxxxiii, lxxxiv.) 



We found it possible to compute this index in 31 skulls only. The extremely short skull, H. 

 216, which gave such a high cephalic index, gave the still higher vertico-longitudinal index of 

 101.39, which was the maximum of the series; but it was not the noi'mal skull with the lowest 

 cephalic index (H. 209) that had the minimum vertico-longitudinal of 74.05. The variation of 

 this index in the series of 31 is greater than in the Saladoan series of 39, and the average of the 

 one series exceeds that of the other by 5 units. 



The cephalic index and the vertico-longitudinal index of the Cibolau group are exactly the 

 same in two cases* and they are within a unit of one another in 5 cases niore.t The close corre- 

 spondence of the maxima, the minima, and the averages in both indices may be seen by consulting 

 Table Lxxxiii. 



5 39. PLANE OF THE FORAMEN MAGNUM. CIBOLA. 



In 27 skulls of this series we have been able to estimate the angle of Daubenton and the 

 analogous basilar and occipital angles of Broca. (See Tables lxxxii, lxxxv.) 



We found in the skulls of the Salado the highest expressions of these angles — higher than 

 any previoiisly on recoid, and we had thought that this might be a concomitant of the occipital 

 distortion and due to pressure on the occiput in infancy, which caused the plane of the foramen 

 magnum to incline more posteriorly. In the skulls of Cibola there is, to judge from the cephalic 

 indices, as much of this flattening as among those of the Salado, yet the angles which indicate 

 the inclination of the jjlane of the foramen magnum are not nearly so great in the former as in the 



* Nos. H. 215 and H. 228. t Nos. H. 202, H. 213, H. 216, H. 217, H. 226. 



