285 



as in the adult skull nearly the whole orbit lies behind this line. 

 As to the topograph}^ of the orbits with regard to the cranial cavitj, 

 in man no change is observed during growth, such as was found 

 with the Anthropoids. We come to the same conclusion when com- 

 paring the anatomy -of the lateral wall of the orbits in the two figures. 

 When dealing with the Gorilla skulls it was pointed out that in 

 the infantile skull two parts could be distinguished in this wall, an 

 intracranial part, partitioning the orbital and cranial cavities, and 

 an anterior part, bordering the orbit outwardly. Between these two 

 parts the cranial wall joins the orbital wall. In the adult Gorilla 

 the intracranial part has disappeared, the cranial wall is attached 

 to the posterior part of the orbital wall. 



In man iiothing apj)ears of these altered anatomical relations. As 

 well in the young as in the adult skull the intracranial part is found, 

 which means that in the adult as well as in the infantile skull the 

 posterior part of the lateral wall of the orbit has remained a parti- 

 tion between this and the cranial cavity. In man the orbital cavity 

 always enters into the cranial cavity, which is moreover proved by 

 the fact that the frontal wall of the cranial cavity is attached along 

 the anterior border of the roof of the oibital cavity, as well in 

 infantile as in adult skulls. 



Thus in regard to the phenomena of growth in the orbital region 

 of the skull there is a very noticeable difference between man on 

 one side and the Anthropoids on the other. This difference is that 

 in man infantile topographical relatioris remairi permanent. In their 

 juvenile slage these relations are the same in man as in the antro- 

 poid apes. While in these latter they are replaced by other relations, 

 however, so that the adult skull becomes very unlike the infantile 

 one, the human skull retains its infantile cranial characteristics. As 

 has been stated in the beginning of this paper, the same holds good 

 for the Foramen magnum. From this ensues that when we compare 

 the human and anthropoid skull those of the anthropoid apes may 

 not be considered as pi-imitive forms from which the human skull 

 should be derived. 



19 



Proceedings Royal Acad. Amsterdam. Vol. XXI. 



