420 



MAMMALIAN ANATOMY 



and sharp outer cingular elevation. This tooth is replaced by the 

 permanent second premolar, which is not a sectorial tooth. 



The second upper deciduous molar (Figs. 340, 341) is like the 

 permanent molar, but more complicated. It has three slender fangs, 

 whereof two are external and close together and one is internal and 

 widely divergent. 



The crown is triangular ; broad along the anterior inner edge 

 and narrow without and behind. The outer anterior angle is the most 



FIG. 341. 



Incisors. 



-w/ If/ 



Third Molar. 



Second Molar. Canine. 



RIGHT UPPER DECIDUOUS TEETH. OUTER ASPECT. 



prominent, and is nearer the outer side of the jaw than is the outer 

 posterior angle. The inner angle presents an inconspicuous cingular 

 cusp, which is separated by a groove from the outer and more important 

 part of the crown. This part is crescentic ; on the inner arcuate edge 

 is a tubercle, which is connected by sharp curved lines with the pointed 



FIG. 342. 



First Molar. 



Second Molar. 



RIGHT LOWER DECIDUOUS TEETH. OUTER ASPECT. 



external angles and by a middle straight line with the emarginate 

 external border. Between the lines the surface is excavated. 



The lower deciduous incisors (Figs. 339, 342) are very small ; 

 their crowns present three cusps, with the middle and external cusps 



