"What is the time of their appearance? The two central lower teeth are usually the first to appear and come from the fifth to the ninth month; next are the four upper central teeth which come from the eighth to the twelfth month. The other two lower central teeth and the four front double teeth come from the twelfth to the eighteenth month. Then follow the four canine teeth the two upper ones being known as the "eye teeth" and the two lower as the "stomach teeth"; they generally come between the eighteenth and the twentyfourth month. The four back double teeth which complete the first set come between the twenty-fourth and thirtieth month. At one year a child usually has six teeth. At one and a half years twelve teeth. At two years sixteen teeth. At two and a half years twenty teeth