7QB REPORT— 1903. 



I would suggest a spot in the median line of the supra-glabellar fossa which 

 is crossed by a transverse line uniting the posterior borders of the external angular 

 processes of the frontal bone. I admit this plan is not free from objections, but 

 it possesses the advantages of being available for both male and female skulls, 

 In my male skull the selection of tliis point diminishes the leogth of the cranium 

 by 25 mm., thus reducing it to lo7 mm. The breadth being calculated at 114 

 mm., the index i.s 8-3-21, and hence distinctly brachycephalic. The length of 

 the cranial cavity is 118 mm. and the breadth OG ram., and the length-breadth 

 index is thus the brachycephalic one of 81'3G. 



1 have given these somewhat detailed references to the measurements of this 

 gorilla's skull because they show in a verj^ clear and obvious manner that from 

 an external examination of the skull one might easily be misled as to the size and 

 form of the cranial cavity, and that, in order to determine from external measure- 

 ments the proportions of the cranial cavity, skull outgrowths due to other 

 factors than brain growth must be rigorously excluded. Further, these details 

 will serve to emphasise the interesting fact that the gorilla's skull is decidedly 

 brachycephalic. This character is by no means restricted to the gorilla, for it 

 has been clearly proved by Virchow, Schwalbe, and others that all the anthropoid 

 apes are markedly round-headed. Ever since the introduction by the illustrious 

 Swedish anthropologist Anders Ret/.ius of a classification of .skulls according to 

 the proportions between their length and breadth great attention has been paid 

 to this peculiarity in diflerent races of mankind. It has been generally held that 

 bracbycephaly indicates a higher type of skull than dolichocephaly, and that the 

 increase in the size of the brain in the higher races has tended to produce a 

 brachycephalic skull. When the cranial walls are subject to excessive internal 

 pressure, as in hydrocephalus, the skull tends to become distinctly brachycephalic, 

 as a given extent of wall gives a greater internal cavity in a spherical than an 

 oval form. In estimating the value of this theory as to the evolutionary line upon 

 which the skull has travelled, it is obvious that the brachycephalic character of 

 the skulls of all the anthropoid apes is a fact which requires consideration. 



Although an adult male gorilla such as I have selected presents in an extreme 

 degree outgrowths from the cranial wall masking the true ibrm of the cranial 

 cavity, the same condition, though to a less marked extent, is met with in the 

 human subject. Further, it is interesting to note that the length of the skull is 

 more liable to be increased by such growths than the breadth, since they occur 

 especially over the lower part of the forehead and to a less degree at the back of 

 the sliull, while the side walls of the cranium in the region of its greatest breadth 

 generally remain thin. 



Few if any fossils have attracted an equal amount of attention or given rise 

 to such keen controversies as the ' Neanderthal ' and the * Trinil ' skull-caps. 

 According to some authorities both these skull-caps are undoubtedly human, 

 while others hold that the ' Neanderthal ' belongs to an extinct species of the 

 genus Homo, and the ' Trinil ' is the remains of an extinct genus — Pithecanthr(rpus 

 ei'ectus of Dubois — intermediate between man and the anthropoids. One of the 

 most obvious and easily recognised peculiarities of these skull-caps is the very 

 marked prominence of the supra-orbital arches. The glabella-occipital length of 

 the Neanderthal is 204 mm., and the greatest transverse diameter, which is over 

 the parietal region, is 152 mm. — an index of 74'51 — while the much smaller 

 Trinil calvaria, with a length of 181 mm. and a breadth of 1.30 mm., has an index 

 of 71'8. Both of these skulls are therefore slightly dolichocephalic. 8chwalbe 

 has corrected these figures by making reductions in their lengths on account of 

 the frontal 'outworks,' so that ho estimates the true length-breadth index 

 of the Neanderthal as 80 and that of the Trinil as 7o-5. These indices, thus 

 raised about 5 per cent., are considered to represent approximatelj? the length- 

 breadth index of the cranial cavity. A comparison of the extei-iijl and internal 

 measurements of many recent slculls with proiniuent glabellre would, I suspect, 

 •show a greater difference than that calculated by Hchwalbe for the Neanderthal 

 and Trinil specimens. In a male skull, probably an aboriginal Australian, with 

 a cranial capacity of 1227 c.cm. I found that the glabella-occipital length was 



