172 THE SKULL. [CHAP. 



a minute groove deep in the recess of the foramen lacerum 

 posterius. In the smaller Cats, this groove is more super- 

 ficial, but always very minute, and apparently never converted 

 into an actual foramen, except by the contiguous wall of the 

 basioccipital. 



The paroccipital process is flattened over the back of the 

 bulla, being applied closely to the whole of its prominent 

 rounded hinder end, and projecting, as a rough tubercle, 

 slightly beyond it. From the inner side of this process a 

 sharp ridge runs towards the occipital condyle. This forms 

 the posterior boundary of a deep fossa, at the bottom of 

 which is the foramen lacerum posterius, and in the hinder 

 part of which, under cover of the aforesaid ridge, the 

 condylar foramen "opens. The mastoid process is a 

 moderately conspicuous rough projection, not very widely 

 separated from the paroccipital. There is no distinct 

 glenoid foramen. 



The Viver rider, agree with the Felidce in having the auditory 

 bulla divided into two cavities by a bony partition, in having 

 the paroccipital spread over the hinder surface of the bulla, 

 and in having no prolonged external auditory meatus ; but 

 the bulla is more elongated and compressed, and the inner 

 chamber is placed altogether behind the outer or true 

 tympanic chamber. 



In the Hy?ena this region of the skull much resembles the 

 same part in the Cats, but the bulla is simple and undivided. 

 In the Dogs there is a partial septum, and otherwise the 

 characters are intermediate between the two extremes of the 

 Bears on one side, and the Cats on the other. 1 



1 For the various modifications of the structure of this part of the 

 skull in the different genera of the order, see "On the Value of the 

 Characters of the Base of the Cranium in the Classification of the Order 

 Carnivora." (Proc. Zool. Soc. 1869, p. 5.) 



