THE SKELETON IN MAMMALIA. THE SKULL. 479 



The cranial cavity though rather depressed is large, and 

 generally long, though in Cats it is comparatively short and 

 wide. The occipital plane is nearly vertical, and the exocci- 

 pitals are developed into fairly prominent paroccipital processes. 

 The interparietal is commonly distinct, and the parietals unite 

 in a long sagittal suture, which is often developed into a crest. 

 The nasals (fig. 73, 4) are well developed, especially in Cats, and 

 the nasal processes of the premaxillae do not nearly reach the 

 frontals. A considerable part of the palate is formed by the 

 palatine, and the maxillary portion is pierced by rather long 

 anterior palatine foramina. The pterygoid has a hamular 

 process. The zygomatic arch is strong, especially in Cats. 

 Postorbital processes are developed on the frontal (fig. 73, 

 10) and jugal, but never form a complete postorbital bar. A 

 carotid canal is well seen in the Ursidae, and to a less extent 

 in the Felidae ; in the Canidae there is an alisphenoid canal 

 (fig. 75, 21). 



The auditory bulla differs a good deal in the different 

 groups. In the Bears (Ursidae) it is not much inflated, and 

 is most prominent along its inner border ; it is not closely con- 

 nected with the paroccipital process. In the Cats it is very 

 prominent, and its cavity is almost divided by a septum into 

 two parts, the inner of which contains the auditory ossicles. 

 The paroccipital process is closely applied to the bulla. In the 

 Dogs the bulla is intermediate in character between that of 

 the Cats and that of the Bears ; it is partially divided by a 

 septum, and is moderately expanded. 



The mandible is well developed with a prominent angle 

 (fig. 72, 26), and a large coronoid process. The hyoid consists 

 of a broad basi-hyal, a long many-jointed anterior cornu and 

 short thyro-hyals (fig. 72, 33). 



The skull in the CREODONTA is in most respects allied to 

 that of the Canidae, but presents some ursine affinities. The 

 tympanic bulla is fairly prominent, but has no well-developed 

 septum. The cranial cavity is very small and narrow, the 



