DEVELOPMENT OF THE SKULL OF BMYS 725 



forward from the anterior apex of the gangHon semilunare, are the 

 nervd nasaHs and frontahs of the ramus ophthahnicus. 



The pila prootica bounds the fenestra prootica in front and on 

 its two sides and forms the posterior margin of the fenestra 

 metoptica. Immediately external to the fenestra prootica, and 

 occluding it almost completely, is the ganghon semilunare whose 

 anterior apex Ues in front of the fenestra. 



The fenestra hypophyseos is semicircular, the transverse front 

 margin of the crista sellaris forming its posterior boundary and 

 the two trabeculae enclosing it laterally and in front. 



The arteria carotis interna enters the cranial cavity through 

 the posterolateral angles of the fenestra hypophyseos which are 

 not excavated to form incisurae caroticae as in Lacerta. The 

 ventral side of the crista sellaris, however, as already noted, bears 

 a broad longitudinal groove on each side of the middle line, 

 the sulcus palatinus, in which the arteria carotis interna, together 

 with the ramus palatinus n. faciahs, lies; so that the extreme 

 anterior end of the sulcus where the artery turns dorsally to enter 

 the fenestra hypophyseos might be looked upon as an indica- 

 tion of an incisura carotica. Posteriorly the sulcus palatinus 

 continues as the sulcus cavernosus. 



The anterior three-fourths of the fenestra hypophyseos is com- 

 pletely occupied by the hypophj'sis cerebri which has a slightly 

 oblique position so that its anterior surface rests partly upon the 

 subiculum infundibuli in front of the fenestra. 



The subiculum infundibuU arises in front of the fenestra hj-po- 

 physeos from the dorsal surface of the trabeculae as a thin plate 

 made up evidently of two sjmimetrical halves which are sUghtly 

 inclined toward each other in the middle line to form a shallow 

 longitudinal trough. The infundibulum and antero-dorsal end 

 of the hypophysis are supported by this plate. The subiculum 

 infundibuh is triangular, with its apex directed posteriorly and its 

 base anteriorly forming the hinder margin of the fenestra optica, 

 and, with its antero-lateral angles prolonged to form the short 

 pilae metopticae, and with its postero-lateral margins bounding 

 the ventral half of the fenestra metoptica in front The whole 

 subiculum infundibuli inclines rather sharply upward in front, 



JOURNAL OF -MORPHOLOGT, VOL. 23, NO. 4 



