ix.] OF THE DOG. 117 



terminating in the rounded incisor border of the premaxiila 

 (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 supraoccipital (SO), extending between them for 

 about half their length. In front of this the parietals are 



fmmonly united together by bone in old dogs. 

 Anteriorly to the parietals, the upper part of the temporal 

 >sa, the frontal plateau between the orbits, and the upper 

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

 ne. The remaining or lower portion of the temporal fossa 

 formed by the squamosal behind and by the alisphenoid 

 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 line 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 vertical ridge formed by the pterygoid, the 

 pterygoid process of the alisphenoid and the palatine bones, 

 and continuing the outer wall of the narial passage back 

 wards beyond the bony palate. The palatine bone forms a 

 considerable part of the inner wall of the orbit, joining the 

 frontal anteriorly, though separated from it for a considerable 

 space posteriorly by the orbitosphenoid. The lachrymal (Z) 

 appears in the anterior boundary of the orbit, the malar (Ma) 

 oins its outer boundary, and the upper surface of the hinder 



join 



