18 



the orbita is provided with an osseous roof. It is a fact, indeed, 

 that in this part of the skull radical changes have taken place in 

 the topographical relations. These changes nnaj be summarized as 

 follows: in the child-anthropoid, and a fortiori in the fetus, the 

 orbits are situated under the cranial cavity, whereas in the adult thej 

 are for ihe gieater part precerebral. While they are lying under the 

 cranial cavity the bottom of this cavity makes up the roof for the 

 orbits, but when the orbitae are shifted precerebral a new roof 

 is to be formed for an adequate protection of the contents. That we 

 really have to do here with a displacement of the whole content 

 of the orbita anteriorly and not with a simple enlargement of the 

 orbitae, is illustrated by Figs 2 and the folllowing. They represent 

 casts of tlie cranial cavity and orbita, in situ. 



These casts were made in the following way : Copper wire of 

 adequate thickness was stuck through the communications between 

 orbit and cranial cavity ; subsequently the orbit and the cranial 

 cavity were filled with plaster of Paris. Finally the enclosing skeleton 

 was cautiously removed with a chisel. In this way an exact image 

 is obtained of the topographical relations between the cranial cavity 

 and the orbita. 



