440 ZOOLOGY SECT. 



(p. max) large bones which form the anterior part of the snout, 

 bear the upper incisor teeth, and give off three processes a nasal, 

 a palatine (pal. p. max), and a maxillary. The maxilla (max.), 

 which form the greater part of the upper jaw, and bear the pre- 

 molar and molar teeth, are large, irregularly-shaped bones, the 

 outer surfaces of which are spongy. They give off internally 

 horizontal processes the palatine processes (pal. max) which 

 unite to form the anterior part of the bony palate. Between the 

 premaxillse and maxillae and the palatines on the lower surface 

 of the skull is a large triangular opening divided into two the 

 anterior palatine foramina by the palatine processes of the pre- 

 maxillae. On the outer surface of each maxilla, above the first 

 premolar tooth, is a foramen the infra-orbital (i.o.f.) through 

 which the second division of the fifth nerve passes. A strong 

 process which is given off from the outer face of each maxilla, 

 and turns outwards and then backwards to unite with the zygomatic 

 process of the squamosal and thus complete the zygomatic arch, 

 is a separate bone in the young, the malar oxjugal (ju.). 



The maxillae help to bound the nasal cavities externally, and 

 with each is connected on its inner aspect a pair of thin scroll-like 

 bones the maxillo-turbinals (Fig. 1094, mx. tb.). The rest of the 

 narrow bony palate, forming the roof of the mouth and the floor of 

 the nasal cavities, is formed by the palatine plates of the palatine 

 bones (pal.). The so-called pterygoids (pt.) are small irregular 

 bones, each of which articulates with the palatine in front and 

 with the pterygoid process of the alisphenoid behind : these are 

 probably not the equivalents of the pterygoids of other Vertebrates, 

 but of part of the parasphenoid. The lacrymals (Icr.) are small 

 bones, one situated in the anterior wall of each orbit, perforated 

 by a small aperture the lacrymal foramen. 



In the interior of the skull (Fig. 1094) are three cavities, the 

 two olfactory or nasal cavities, right and left, in front, and the 

 cranial cavity behind. The former are separated from one another 

 by a median partition or septum, partly cartilaginous, partly bony, 

 formed, as above described, by the mesethmoid. Each contains the 

 turbinals or turbinated bones of its side ; it opens on the exterior 

 by the large external nasal aperture, and behind it communicates 

 with the cavity of the mouth by the posterior nasal aperture. 



The cranial cavity has its walls moulded to a considerable extent 

 on the surface of the contained brain, and, in consequence, there 

 are to be recognised concavities in the former corresponding with 

 the prominent portions of the latter. These concavities are termed 

 the fossce, and they consist of the cerebellar fossa behind and the 

 cerebral fossa in front, with the inconspicuous olfactory fossa in the 

 frontal region. 



The mandible, or lower jaw, consists of two lateral halves or rami, 

 which are connected with one another in front by a rough articular 



