254 



NATURAL SCIENCE. 



op. 



April, 



pi 



p.v. 



a.( 



pe. c.e 



Teeth of Horse (two- thirds natural size). 



A. Right, upper, fourth premolar of nine-year-old horse. View of table. 



B. External view of same tooth. 



C. Right, upper, third premolar of colt (twenty months) before cutting the gum. End view. 



D. Right, lower, third, deciduous molar of same colt. Side view. 



E. Right, lower, third premolar of eighteen-year-old horse. 



F. Right, lower, fourth premolar of nine-year-old horse. View of table. 



G. External view of same tooth. 



H. Upper, central incisor of six-year-old mare. Anterior view. 



J. Posterior view of same tooth. 



K. Upper, central, deciduous incisor of filly (eight months). Anterior view. 



L. Lower right^canine of nine-year-old horse. 



M. Lower canine of fourteen-year-old mare. 



N. Lower deciduous canine of colt at birth. 



O. Upper first premolar of fourteen-year-old mare. 



a.i., anterior infundibulum ; p.i., posterior infundibulum ; a.p,, accessory, internal pillar. 



p.e., peripheral enamel; c.e., central enamel; rf, dentine; cr, crown; r, root ; », neck; 



i., infundibulum. 



