TOOTH-GENESTS IN" THE CAKID^. 



447 



dates of eruption are as follows : — The first tooth to cut the gum 

 is the lower carnassial (dpm?), and this is quickly succeeded by the 

 upper (dpm.^). The former just makes its appearance about the 

 end of the second week. By the end of the third week these 

 teeth are well througb and dpm? and 'c. are commencing to 

 appear, the former slightly preceding the latter. These are soon 

 followed by ^- and ^, which cut tlie gum at nearly the same time. 

 dpm-^ appears next, and about the same time clpm.^ These are 

 followed by the remaining upper incisors, and then by the lower 

 incisors. The last deciduous tooth to be erupted is dpm7, which 

 does not appear until nearly the third month. 



Fig. 1. 



Deciduous dentition of Canis familiaris, seen from the left side. 

 Lettering explained in the text. 



Upper Teeth. — The three upper incisors increase somewhat in 

 size from within outwards, but they are all of the same pattern. 

 When viewed anteriorly their crowns may be likened to a " fleur- 

 de-lis," consisting of a main central cone with a small, but well- 

 marked cusp on each of its sides (fig. 1, ca and cp). On the 

 internal face there is a tvell-marked cingulum, which is seen to 

 be continuous with these smaller cusps. On comparing the 

 outer with the central incisors, it will be seen that the ante- 

 rior (inner) cusp has a decided tendency to reduction or non- 



