192 Charles Searing Mead. 



bulla with its adjoining foramina (foramen Glaseri and foramen 

 stylomastoideum) ; and an incomplete development of certain of the 

 cartilage formations, namely, the tegmen tympani and the distal 

 two-thirds of the canalis facialis. The connection of the malleus 

 with Meckel's cartilage still persists in the embryo at this stage. 



Regio Orbitotemporalis. 



The orbitotemporal or sphenoidal region may conveniently be 

 divided into the median unpaired basal, and the lateral paired, por- 

 tions. The lateral portions are composed, on each side, of two wings, 

 the posterior or ala temporalis, which ends freely, and the anterior 

 or ala orbitalis, which is attached to the nasal capsule and the lamina 

 parietalis. » 



This region in the embryo differs more from that in the adult 

 skull than any other, with the exception of the cranial roof and the 

 ear-bones. 



In the hinder part of the basilar cartilage is the hypophysial fossa. 

 This marks the anterior extent of the notochord. It is shallow poste- 

 riorly and deeper anteriorly, where it is roofed over for one-sixth 

 of its length by the prominent backwardly-projecting tuberculum 

 ephipi^ii. At a later stage the anterior wall of the fossa slopes back- 

 ward, the partial roofing over just mentioned not being present. But 

 meanwhile the dorsum ephippii and the processus clinoideus posterior 

 have grown forward and now roof it over fivm' behind for fully one- 

 half of its length. 



The alar processes, to be fully described later, are narrow and ex- 

 tend directly outward from the anterior half of the floor of ihe 

 hypophysial fossa. 



From the anterior edge of the hypophysial fossa to the nasal 

 septum the basilar cartilage continues in the same general direction 

 as the basal plate. The basal cartilage is continued backward into 

 the planum basale and forward into the nasal septum, with no sharp 

 boundary setting it off from either. It may be said to extend from 

 the dorsum sellse to the posterior ends of the nasal capsules. Its 

 breadth is nearly uniform, while its height gradually increases from 

 a point in the region under the sella turcica, where it presents 



