THE VERTEBRATE SKELETON. 



FIG. 1. DIAGRAMMATIC SECTIONS OF VARIOUS FORMS OF TEETH 

 (from FLOWER). 



I. Incisor or tusk of elephant, with pulp-cavity persistently open at 

 base. II. Human incisor during development with root imperfectly 

 formed, and pulp-cavity widely open at base. III. Completely formed 

 human incisor, with pulp-cavity contracted to a small aperture at the 

 end of the root. IV. Human molar with broad crown and two roots. 

 V. Molar of Ox, with the enamel covering the crown, deeply folded and 

 the depressions filled with cement. The surface is worn by use, other- 

 wise the enamel coating would be continuous at the top of the ridges. 

 In all the figures the enamel is black, the pulp white, the dentine 

 represented by horizontal lines, and the cement by dots. 



