CHAP. IX.] 



THE SKULL OF THE DOG. 



from each other. For this purpose a young animal, still 

 retaining the milk teeth, will be best.' 



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



jrr ^^ IP 



CE 

 ME 



Fig. 45- — Longitudinal and vertical section of the skull of a Dog {Caiiis famillarh , 

 with mandible and hyoid arch, \. an anterior narial aperture; MT maxillo- 

 turbinal bone; ET fthmo-tnrbinal ; Na nasal; ME ossified portion of the 

 mesethmoid ; CE cribriform plate of the ethmo-turbinal ; Fr frontal ; Pa parietal ; 

 //-* interparietal : SO supr.^occipital ; ExO exoccipital ; BO basioccipital ; Per 

 periotic ; j56" basisphenoid ; Pt pteryg id ; AS aiisphenoid ; C^ orbitosphenoid ; 

 PS presphenoid ; PI paia'ine ; Vo vomer ; ]\Ix maxilla ; PMx premaxilla ; 

 sh stylohval \.ch epihyal ; ch c^ratohyal ; bh basihyal ; th thyrohval ; 5 symphysis 

 of mandible ; cp coronoid process : cd condyle ; a angle ; id inferior 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. 



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

 its structure will be best understood by commencing with 

 the description of the bones forming this axis. 



^ 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. 



H 



