CHAP. IX ] 



THE SKULL OF THE DOG. 



"7 



other. For this purpose a young animal, still retaining the 

 milk teeth, will be best. 1 



The skull has a longitudinal central axis (the cranio-facial 

 axis, Huxley), around which all its parts are arranged, and 



U 



id 



Km. 46 longitudinal and vertical section of the skull of a Do({ (Canit/amiliarii), 

 with mandible ami hyoid arch, J. an anterior narial aperture; MT maxillo- 

 turliiii.il bone; KT ethmo-turbinal ; A'<* nasal; ME ossified portion of the 

 mesethmoid ; CK cribriform plate of the clhmo-turbinal ; /> frontal; Pa parietal ; 

 //' interparietal : SO supraoccipital ; / jcO exoccipital ; BO basioccipital : I'tr 

 periotic ; ItS basisphenoid ; /'/ ptcrygoid ; AS alisphenoid ; OS orbitosphenoid ; 

 PS presphenoid : /'/ palatine ; I'o vomer ; MX maxilla ; PMx premaxilla : 

 sk stylohyal ; tk epihyal ; ch ceratohyal ; bk basihyal ; tk thyrohyal ; s symphysis 

 of mandible ; c/ coronoid process ; <-</condyle ; a angle ; id infenor dental canal ; 

 the mandible is displaced downwards to show its entire form ; the * indicates the 

 part of the cranium to which the condyle is articulated. 



its structure will be best understood by commencing with 

 the description of the bones forming this axis. 



1 When the zoologist wishes to throw into the strongest relief the 

 distinctive characters of different species, he selects for comparison fully 

 adult examples ; when the anatomist wishes to trace their community of 

 structure and their resemblances, younger specimens are better adapted 

 for his purpose. 



