THE SKULL. 51 



crest (e), passes craniad in the middle line across the inter- 

 parietal bone : it varies greatly in extent, reaching in a very old 

 and muscular cat to the cranial border of the parietals, while 

 in kittens it does not exist. The most prominent portions of 

 the skull in this region, just craniad of the middle of the parie- 

 tal bones, are known as the parietal tubercles or eminences (</). 

 A faint curved line (e) runs from the cranial end of the sagittal 

 crest craniolaterad to the base of the zygomatic process of the 

 frontal : it marks the dorsal boundary of the origin of the tem- 

 poral muscle, and may therefore be considered the dorsal 

 boundary of the temporal fossa. This fossa extends from its 

 dorsal boundary as far laterad and caudad as the lambdoidal 

 ridge (a), and as far craniad as a line connecting the tip of the 

 zygomatic process of the frontal (/") with the frontal process of 

 the malar (/*). The temporal muscle takes origin from its 

 surface. 



The middle portion of the dorsal surface is formed by the 

 frontals (5). Each frontal presents laterally a prominent 

 zygomatic process (_/"), extending ventrolaterad toward a cor- 

 responding (frontal) process (//) of the malar bone. These two 

 processes mark the boundary between the orbital fossa (craniad) 

 and the temporal fossa (caudad). Craniad of the zygomatic 

 process of the frontal a sharp margin separates the dorsal sur- 

 face of the skull from the wall of the orbital fossa : this is the 

 supraorbital arch or margin (/). 



The cranial portion of the dorsal surface is formed by the 

 maxillary (s), nasal (7), and premaxillary bones (9). Just 

 craniad of the nasals, bounded ventrad and craniad by the 

 premaxillaries, appears the large opening of tne nares (j), 

 leading into the nasal cavity. 



The zygomatic arch (g) is formed by the zygomatic process 

 of the temporal (;) and the malar or zygomatic bone (G). 

 Each presents near its middle a prominent dorsocaudally 

 directed process, the frontal process (//) of the malar bone. The 

 zygomatic arch forms the lateral boundary of the temporal and 

 orbital fossae, which are separated by a line connecting the 

 frontal process of the malar (/t) and the zygomatic process of 

 the frontal (/). 



