281 



outline of the cranial cavity entirely indicated. Position and direction 

 of the lamina cribosa are also shown. To the transformation of the 

 cranial cavity during- growdi, chiefly consisting- in a flattening, 



Fig. 4. 



Fig. 5. 



attention may be passingly drawn. These figures require little 

 explanation, the change in the topographical relation of the orbits 

 with regard to the cranial cavity is seen at a glance. It should oidy 

 be pointed out that the shifting of the orbits quite before the cranial 

 cavity must be regarded as the direct cause of the origin of the 

 very strong bony ridge characterising the anteiior part of the cerebral 

 skull of Gorilla. This bone-i-idge is, as also appears from tig. 3, 

 nothing but the necessary upward enclosure of the orbital cavity, 

 the newly-grown roof of this cavity. Without this bone-ridge the 

 orbit would lack an upper bony enclosure. 



Before proceeding to a description of the conditions in man, we 

 shall briefly sketch those in the two other anthropoids by means of 

 a few projection figures. Figures 6 and 7 refer to a young Orang 

 still in possession of its complete milk-dentition, and to an adult 

 individual of this genus. More stiongly still than was the case with 

 Gorilla the topographical change of the orbits with regard to the 



