348 



MAMMALIAN ANATOMY 



border near the end of the surface for the frontal. It marks the 

 lower front edge of the plate on the ethmoid which lies behind 

 the ethmoidal cleft on the lateral surface, and limits its superior 

 part in front. Below the line is a groove corresponding to the deep, 

 lateral, triangular ethmoidal cleft on the side of the ethmoid anterior 

 to the plate just mentioned. Above the upper curved line is an 

 irregularly quadrate space, joined to the upper border by a narrow 

 strip. To this part the plate of the ethmoid and its upward extension 

 are attached. 



The Malar Process (Figs. 265, 271) appears in the form of an 

 upward and outward extension of the orbital surface and an upward 



FIG. 272. 



Posterior part of Frontal Sinus. Sagittal Suture. 



\ 



Orbital Ridge. 



Opening into Anterior part of Frontal 

 Sinus, with Posterior end of Lat- 

 eral Ethmoid. 



Foramina for Olfactory Filaments. 



Median Plate of Frontal. - 



Orbital Plate of Frontal. 



Cut Edge of Cribriform Plate. 



Cribriform Plate of 

 Ethmoid. 



Mesethmoid 



Vertical Plate of Pala 

 tine. 



Lateral Ethmoid. 



Vomer 

 Lachrymal 



Lachrymal Canal. 



Alveolar Border. 



Zygoma. 



Maxillary 



Tuberosity. Infraorbital 

 Foramen. 



TRANSVERSE VERTICAL SECTION OF SKULL THROUGH ORBITS, SEEN FROM BEHIND. 



and outward extension of the back part of the external surface. 

 Between the two parts is a deep fissure which receives the anterior 

 border of the malar. This fissure is wide in front and narrow behind. 

 For the greater part of its extent it is at the upper edge of the process, 

 but at the posterior part it lies on the external surface. Its outer 

 lip is sharp, arched, and directed outward, but becomes indistinct as 



