XIII 



PHYLUM CHORDATA 



513 



In the skull of the Carnivora vera (Figs. 1097 and 1099) there 

 are prominent sagittal and lambdoid.il crests. The temporal 

 fossae are very deep ; the 

 orbits are not separated 

 from them by bone. The 

 relative development of the 

 facial region varies in the 

 different groups ; in the 



FIG. 1097. Skull of Tiger (Felis 

 Blainville.) 



(After 



Bears and their allies, and 



in the Dogs, it is elongated ; 



in the Cats it is very short. 



The zygoma is strong and 



greatly arched outwards. 



The glenoid cavity is in the 



form of a transverse groove 



to the shape of which the 



transversely elongated con- 



dyle is adapted. In the 



Cats there is a large rounded 



tympanic bulla (Fig. 1098), 



the cavity of which is 



divided into two parts, an- 

 terior and posterior, by a 



septum, the anterior con- 

 taining the auditory' ossicles and the opening of the Eustachian 



tube; the bony auditory meatus is short : the paroccipital is closely 



applied to the posterior surface of the tympanic bulla. In the 



Dogs the septum of 

 the bulla is incom- 

 plete, the auditory 

 meatus short, and 

 the paroccipital pro- 

 cess not applied to 

 the bulla. In the 

 Bears and their allies 

 (Fig. 1100), the bulla 

 is usually less dilated, 

 and the septum is 

 absent or only re- 

 presented by a ridge, 

 while the bony audi- 

 tory meatus is elon- 

 gated. 



The cranium in 

 the Pinnipedia is 

 broad and rounded, 

 rather compressed 



oo 



Fin. 1098. Section of the left auditory bulla of Tiger (Felis 

 tigris). a. aperture of communication between the two 

 chambers into which the cavity of the bulla is divided ; 

 a. m. external auditory meatus ; b. oc. basi-occipital ; Pt. 

 periotic ; s. septum between the two chambers ; Sq. 

 squamosal. (After Flower.) 



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