62 ANTHROPOID APES. 



is brachycephalic, but that this characteristic 

 diminishes with increasing age, at any rate, if the 

 external excrescences are taken into account. But it 

 is quite otherwise when the furthest point of measure- 

 ment is taiten from the frontal arch, not from the 

 nasal prominence. In such a case the increase of 

 the brachycephalic condition is established.* 



In the skulls of such young males as those here 

 mentioned, the temporal ridges, which in aged animals 

 are in close proximity in the region of the developed 

 bony crests, have already in some cases begun to 

 approach each other, but they are still far apart. In 

 young specimens we can distinguish, on each side 

 of the parietal bones, two temporal ridges, opposite 

 each other, and taking a nearly parallel course. 

 The upper ridge, which loses itself on the external 

 surface of the mastoid process, which is already 

 developed, corresponds to the junction of the fascia 

 of the cranial muscles {Galea aponeurotica musculi 

 epicranii) with the fascia enclosing the large tem- 

 poral muscles. The lower ridge, which is gradually 

 merged in the upper edge of the zygomatuTprocess 

 of the temporal bone, forms the demarcation of the 

 fleshy origin of the temporal muscle. This corre- 

 sponds to the spot at which the two layers of the 

 temporal fascia unite. In a very young male these 

 temporal ridges can be only faintly traced ; they be- 

 come more strongly marked as his growth advances, 

 and as they approximate more closely to each other 

 on the vertex of the cranium, I have examined a 



* Monthly report of the Eoyal Academy of Sciences, Berlin, 

 June 7, 1880. 



