,598 eeport — 1878. 



by reference to drawings of the young and adult gorilla skulls, and those of other 

 animals and of man, the necessity and advantages of such a standard in enabling the 

 observer to make accurate corresponding representations and measurements of di- 

 mensions and directions. The resemblance of the view taken in the norma facialis 

 of the infantile gorilla to the human skull was very striking. 



In its general form this skull, as belonging to the infantile age, like that of its 

 congeners and of man, differs remarkably from that of the adult ; and in the case of 

 the gorilla and orang, more particularly of the male, in the proportionally large size 

 of the cranial part, the smaller size of the face, jaws and teeth, and in the entire 

 absence of the crests of bone which attain such an enormous size in the adult male 

 gorilla. In the infantile condition there is probably little or no difference in the 

 form of the skull in the two sexes ; but as age advances, and more especially as the 

 second dentition appears, the distinctions arise by the greater development of the 

 jaws and by the gradual approach and elevation of the temporal ridges, which remain 

 distinct in the female, but rise into the sagittal and occipital crests of the male. In 

 the skull shown there was as yet no appearance of the temporal lines, except in the 

 commencement at the zygomatic process of the frontal bone. The double ridges on 

 each side described by recent authors come to be obvious only at the change of the 

 dentition. 



For comparison with the human form the skull of a child of about two and a 

 half years of age with the first dentition recently completed was employed, and 

 many points of [interest were brought out. Among these the capacity of the cra- 

 nium may be mentioned. 'That of the child's skull now referred to was 64 cubic 

 inches, that of the infantile gorilla 28|, while the average adult human skull may be 

 stated at 85 cubic inches, and that of the adult male gorilla at 33, and of the female 

 at 28 cubic inches. 



The author then referred more particularly to a point in the osteology of the 

 skull which had excited considerable interest since the researches of Virchow and 

 Gruber had thrown some light upon it, viz. the mode of union of the several bones 

 which meet at the antero-lateral fontanelle of the foetal skull, or the ptereon of Broca. 

 It is now known that considerable differences in this respect occur in the human 

 skulls of the same and different races of men, and it has long been known (Owen) 

 that among the anthropoid apes there are differences of a similar kind, and that 

 these differences are in some instances at least connected with the existence of a 

 separate bone in the seat of the place of meeting at the ptereon, of the frontal, 

 parietal, squamous, and alisphenoid bones, to which the name of epipteric has been 

 given by Professor Flower. 



In the great majority of human skulls, as well known to anatomists, the anterior 

 inferior angle of the parietal bone joins here the alisphenoid in a greater or less ex- 

 tent,* and thus excludes the frontal and squamous bones from mutual union ; while 

 in a smaller number of instances the alisphenoid and parietal are separated by the 

 junction of the squamous and frontal bones. 



Now, in the gorilla, as shown in the skull exhibited, and in nine other skulls of 

 the same animal examined by the author, the mode of union at the ptereon is in- 

 variably squamo-frontal. In the chimpanzee he found the same land of union to 

 prevail as in the gorilla in 23 out of 27 skulls examined ; but in two examples the 

 union was spheno-parietal on both sides, and in two others it was squamo-frontal on 

 one side and spheno-parietal on the other. 



In the orang, again, a greater difference was observed, for out of 30 skulls 

 observed, the spheno-parietal union was present on both sides in 16, and the squamo- 

 frontal in 7, while in 4 the mode of union was different on the two sides, and in 3 

 there existed the intervening epipteric bones, occupying as it were the common 

 territory. 



In 9 skulls of the Gibbon examined, 8 presented the spheno-parietal mode of 

 union, and in the other case there was unilateral squamo-frontal union with an 

 epipteric bone on the opposite side. 



* The author referred here to the differences observed in tlte human skull, but 

 as he is engaged in unfinished observations on this subject, he reserves their de- 

 scription for another opportunity 



