SKULL OF A HUMAN FETUS OF 40 MM. 397 



evidences of the medial attachment of the primitive side-wall 

 of the orbitotemporal region in the form of three rudimentar}^ 

 cartilages, and membrane connecting them, and stretching out 

 from them. From behind forward he finds, first, Restknorpel a, 

 surmounting the commissura suprafacialis (continuous with 

 this on one side but not on the othfer), next Restknorpel b, over- 

 lying the semilunar ganglion, and connected by a sheet of con- 

 nective tissue, which overlies the abducens nerve, with the pillar 

 of the dorsum sellae. Restknorpel b is quite free. A third 

 rudimentary cartilage, Restknorpel c, appears only on the left 

 side of Voit's youngest rabbit skull, and this fact appears to 

 point to its transient nature. It presents itself at about the site 

 apparently of the middle clinoid process, and is attached directly 

 to the side of the Balkenplatte. Between Restknorpeln b and c 

 the boundary betweeji the primitive cranial cavity and the cavum 

 epiptericum is not clearly marked. From these three Rest- 

 knorpeln, and from the cartilage intervening, anchorage is 

 afforded for a stout sheet of connective tissue which stretches 

 outward and upward to find its cranial attachment in the lower 

 edge of the taenia marginalis, or, as Voit calls it in this region, 

 the commissura orbitoparietalis. Underlying this membrane, 

 which Voit thinks is, to some extent, the precursor of the dura 

 mater of this region, are several important structures which are 

 prunarily outside of the primitive brain case, as in the lizards, 

 but are later taken into the brain case of the mammals; among 

 these have already been mentioned the semilunar ganglion and 

 part of its nerve trunks, part of the facial nerve, the geniculate 

 ganglion and part of the great superficial petrosal nerve. In 

 addition might be mentioned the nerves to the eye muscles, and 

 the internal carotid artery — indeed all the structures in the 

 cavernous sinus. The carotid artery is shown in the youngest 

 stage of Voit winding around the caudo-ventral surface of Rest- 

 knorpel c to enter the primitive cranium, this point marking its 

 original inlet. 



From the researches of Voit it would appear that the new 

 floor and side-wall of the cavum epiptericum and the cavum 

 supracochleare a^-e formed by the upper part of the ala temporalis. 



