MAMMALIA 



469 



tips of the incisors is folded in, so as to form a pit. This gives rise to 

 a marking which alters as the teeth wear down, and enables the age of 

 the animal to be told. 1 



Fig. 34S. — The lower surface of a dog's skull. — From Thomson 



o.c, Occipital condyle; B.C., basioccipital ; T., tympanic bulla; m.c. 

 postglenoid process behind fossa for condyle of mandible ; B.S., basi 

 sphenoid ; P.S., base of presphenoid ; V., vomer ; M.2, second molar 

 M.i, first molar; /V/z.1-4, premolars, the 4th the large carnassial 

 c, canine; /.1-3, incisors; Pvix., premaxilla ; mx., maxilla; Pal., 

 palatine;/., jugal ; A.S., alisphenoid ; Pt., pterygoid; Sq., squamosal 

 (the reference line points to the glenoid fossa). 



1 The dates of appearance and replacement of the teeth are also 

 of use in judging the age of a horse. The incisors of the first pair are 

 fully cut at one month, all three pairs at a little over one year. The 

 first pair are replaced after two and a half years. The canines (tushes) 



