244 MAMMALIAN DENTITION 



not exactly true. In both jaws the second milk molar has an 

 occlusal surface relatively narrow compared with the crown 

 because of the marked beveling of the latter upon its outer 

 side. The maxillary tooth is neither so rhomboidal nor so 

 obliquely set in the jaw as the corresponding first permanent 

 molar. It possesses a very large protocone and relatively 

 small paracone and metacone, the oblique ridge between the 

 latter and the first mentioned being present as in the permanent 

 molars. The hypocone is small though distinct. The crown of 

 the lower tooth is relatively very long, the lateral grooves be- 

 tween the cusps are deep and the cusps well separated: the 

 talonid is broader than the trigonid. The protoconid and hypo- 

 conid are small and the metaconid very large so that the cross 

 furrows so typical of the permanent molars do not exist. The 

 entoconid is of moderate size and the hypoconulid not axial but 

 lateral in position. 



If now the features just described be compared with those 

 of the permanent molars already interpreted in Chapter VII, 

 it will be seen at once that they form a curious mixture of 

 ancestral and specialized characters. Whereas the features of 

 the second upper milk molar and the arrangement of cusps 

 (except the hypoconulid) of the lower second may well be 

 considered primitive, the reduction in size of the occlusal sur- 

 face from that of the crown proper and the lateral position of 

 the hypoconulid cannot be so regarded. Hence the dispropor- 

 tionate length of the occlusal surface of the second lower molar 

 is secondary in origin. The interpretation of the first premolar 

 is not so simple and must be deferred for the moment. 



When we turn to the milk dentition of the modern Negro 

 we find that the description given above for the temporary 

 teeth of the European holds fairly well and there is no need for 

 special description. 



In Paleolithic types we have not many examples of milk 

 teeth, but from the accompanying figure of the mandible 

 of a child about seven years old discovered in an upper Paleo- 



