ix.] OF THE DOG. 137 



This is the postorbital process of the frontal bone. It is con- 

 nected by a ligamentous band, in the living animal, with a 

 corresponding process arising from the zygoma ; but when 

 this is removed the orbit and temporal fossa are widely 

 continuous, their respective limits being only indicated by 

 the above-mentioned processes. 



The face is produced considerably in front of the orbits, 

 and not only becomes more depressed, but also more com- 

 pressed laterally, and is obliquely truncated anteriorly, 

 terminating in the rounded incisor border of the premaxilla 

 (PMx) ; above which is placed the subcircular orifice of the 

 anterior nares. 



The upper, and a considerable portion of the lateral surface 

 of the cranium behind is formed by the parietal bones (Pa), 

 having the narrow interparietal (IP) ankylosed with the supra- 

 occipital (SO), extending between them for about half their 

 length. In front of this the parietals are commonly united 

 together by bone in old dogs. 



Anteriorly to the parietals, the upper part of the temporal 

 fossa, the frontal plateau between the orbits, and the upper 

 half of the inner wall of the orbit, are formed by the frontal 

 bone. The remaining or lower portion of the temporal fossa 

 is formed by the squamosal behind and by the alisphenoid 

 in front. On the inner or cranial surface of the confluent 

 orbital and temporal fossae, a wide groove runs obliquely 

 downwards and backwards, which may be considered as the 

 boundary lines of these two regions. In the lower part of 

 this groove are several large- foramina placed in linear series. 

 The highest is the optic foramen, the next (of larger size) the 

 sphenoidal fissure, and the third the foramen rotundum and 

 anterior opening of the alisphenoid canal. The orbit has no 

 floor except for a very short space in front ; the lower border 

 of its inner wall passing directly into the outer surface of the 



