318 ROBERT J. TERRY 



sella turcica the basis cranii is bent in a sagittal plane so that the 

 otic and orbital portions form an angle, open ventrally. Also, 

 where the orbito-temporal portion of the base goes over into 

 the septum nasi, a similar angle is formed. 



At the level of the sella turcica the base is flattened dorso-ven- 

 trally, becomes thicker opposite the optic foramina and finally 

 triangular in its most anterior part. Here, the two extracranial 

 surfaces inchne medially and ventrally to meet in a keel, forming 

 a short interorbital septum which passes forward into the sep- 

 tum nasi. 



Sella turcica (figs. 1, 23). The elongate, shallow pitiutary fossa 

 is limited anteriorly by a low tuberculum sellae and posteriorly 

 by a well defined wall. The base of the latter is made by the 

 crista transversa extending nearly to the cochlear capsules, a 

 slight interval remaining between these parts transmitting the 

 abducent nerve. The dorsum sellae is represented by a conical 

 elevation of the middle of the crista transversa. Remains of a 

 hypophyseal canal are present and are occupied by epithelial 

 vestiges of the stalk of the anterior lobe of the pituitary body. 



Ala temporalis (figs. 1, 2, 3, 4, 23). The ala temporahs of the 

 23.1 mm. embryo extends from the processus alaris of the basis 

 cranii, opposite the sella turcica, outward bfeneath the semilunar 

 ganglion; it is limited by free margins in front and behind. Its 

 structure is of young cartilage separate from that of the proces- 

 sus alaris, a stratum of mesenchyma standing between them. 

 The temporal wing consists of a larger blade-formed lateral por- 

 tion, the lamina ascendens, and a small, medial pterygoid proc- 

 ess. A separate pterygoid cartilage is present, lying mesad of 

 the pterygoid process below the basis cranii. In connection with 

 the description of the ala temporalis the cavum epiptericum will 

 be considered. 



Processus alaris (figs. 2, 23). The alar process lies in front of 

 the carotid foramen, supports the internal carotid artery in its 

 forward course and forms the ventral boundary of the innermost 

 part of the spheno-orbital fissure. Laterally it extends to the 

 temporal wing, the layer of mesenchyma above mentioned limit- 

 ing the two parts (fig. 23) . This layer takes an oblique direc- 



