HIGH SCHOOL ZOOLOGY. 140 



tlie uiuon of tlie frontal and jugals, the strength of the jiignl 

 pi-ocosses of tho niaxillaries, and of the alveolar parti? of these 

 l:)ones, the liard palate with tlie incisive foramina between tlio 

 nasal and nioutli cavities, and the concealment of the vomex*s by 

 the palatines, the foramina for the escape of the various ci-anial 

 nerves, that in the lachrymal bone for the passage into the nasal 

 cavity of the tear-duct, and, finally, the intracranial aspect of the 

 various bones, with the ossified partition (tentorium cerebelli) 

 which separates the cerebrum from the cerebellum, and tlie 

 hollow on the upper surface of the basisphenoid (sella turcica) 

 for tlic accomodation of the hypophysis. 



Certain muscular processes on the lower jaw, esi)ecial]y the 

 coronoid process to wliich the temi)oral muscle is attached, iu- 

 dicate the powerful character of the parts concerned. The 

 articular surfiice of the mandible is convex, and elongated trans- 

 versely; it fits into a corresponding concavity (glenoid) bounded 

 behind by a ridge (postglenoidal) on the root of the zygomatic 

 process of the temporal bone. It is a question whether tliis j)art 

 of the temporal bone is comparable to the quadrate of tho lower 

 forms or not. The fact that the Meckelian cartilage is con- 

 tinuous in develoi)ment with one of the chain of bones within 

 the drum of the ear (the malleus) caused anatomists to believe 

 that, in comparison with the Sauropsida, the Mammalian man- 

 dible has shifted its articulation to the squamosal, but this con- 

 tinuity is not irreconcilable with the interpretation of the glenoid 

 region of the temporal as the quadrate. 



The complex visceral skeleton of the fish is only re[)resented 

 in the Mammal by the hyoid bone and its two pairs of cornua. ' 

 Both of these are attached to the extremities of a curved basal 

 piece, the anterior representing the hyoid, the posterior the first 

 branchial arch of the lower forms. The former is attached to 

 the temporal region of the skull, and often unites with it form- 

 ing a bony process (stylo-hyoid) of the temporal bone. In the 



