36 Dr. Cleland on the Variations of the Human Skull. [June \~> 



foramen magnum, orbital length or profile distance of fronto nasal suture 

 from foramen opticum, and the foramino- optic line uniting the other lines 

 together, it is found that the long base-line of savage skulls depends both 

 on amount of orbital length and on long foramino-optic line. 



4. The angle at which the line of orbital length lies to the foramen 

 magnum is distinguished as the cranial curvature. This angle in adult Eu- 

 ropeans on an average exceeds 180°, and in negro and other savage types 

 falls short of that amount. It is also less in infants than in adults, and 

 greater in females than in males. But the variation of the angles at which 

 the foramen magnum and orbital depth respectively lie to the foramino- 

 optic line, is much greater than the variation in cranial curvature ; therefore 

 the two angles mentioned are in a certain degree of mutual relation ; and 

 according to their size, the base may be termed " steep " or " level." The 

 infant base is much more level than the adult male base ; the levelness of 

 childhood sometimes persists in the female. 



5. The different regions of the arch do not grow equally. The parietal 

 region reaches its greatest predominance in the last month of fcetal life, 

 and after birth the frontal region grows most rapidly, and the occipital 

 region next most rapidly. There is no foundation whatever, so far as mesial 

 measurements are concerned, for the supposition that the lower races of 

 humanity have the forehead less developed than the more civilized nations. 

 Neither is it the case that the forehead in the lower races slopes more 

 backwards on the floor of the anterior cranial fossa than it does in others. 



6. The local prominence of different parts of the arch of the skull being 

 measured by means of the angles joining lines passing from point to point 

 in the arch, it is shown that the angles furnish a means of collecting various 

 precise details with regard to national characteristics of form, from which 

 important results may be expected if the plan be worked on an extensive 

 scale. Flatness of the angle formed by lines from the extremities to the 

 midpoint of the parietal arc is shown to be correlated with length of base- 

 line. 



7. As age advances, "gravitation changes" take place, the base being 

 driven in and the lateral wall bulging out, the forehead becoming more 

 retreating, and the condyles flat. 



8. It is sought to be shown that if Dolichocephali and Brachycephali 

 are to continue to be a natural and not an artificial division of skulls, the 

 distinction must be based on the various characters pointed out by Retzius, 

 and not on the mere amount of the "cephalic index." The proportion of 

 height to length, according to the writer, is more important than the pro- 

 portion of breadth to length. He proposes that Hindoo skulls should be 

 considered as belonging to a subdivision Brachycephali angustiores, and 

 that the Germans should be considered as Dolichocephali latiores. 



9. The value of " radial" measurements from the postauricular depres- 

 sion is tested, and it is shown that a classification of some value may be 

 based on them, but that they are defective in consequence of the variability 



