510 



ZOOLOGY 



SECT. 



behind. The nasal 

 cavities are very 

 large, especially 

 in the Porcupines, 

 with air sinuses 

 in the upper part. 

 In some the optic 

 foramina fuse into 

 one. An inter- 

 parietal is often 

 present. Par-oc- 

 cipital processes 

 are developed. 

 The orbit and the 

 temporal fossa are 

 always continuous. 

 The nasal bones 

 are large, and the 

 nasal apertures are 

 terminal or nearly 

 so. The pre-max- 

 illse are always 

 very large. A re- 

 markable feature 

 of the skull is the 

 presence in many 

 of a large open- 

 ing corresponding 

 to the infra-orbital 

 foramen. The 

 middle part of the 

 zygoma is formed 

 by the jugal ; the 

 latter often helps 

 to bound the 

 glenoid cavity as 

 in the Marsupials. 

 The palate is short, 

 and the anterior 

 palatine foramina 

 large. The peri- 

 otic and tympanic 

 are ankylosed to- 

 gether, but not to 

 the neighbouring 

 bones. The coro- 

 noid process of the 



