28 MEDICAL JURISPRUDENCE The neck of the femur forms almost a right angle with its shaft in the female, and an obtuse angle in the male, while the head of the femur in the male forms about two-thirds of a sphere, and is larger than that of the femur in the female. 3. AGE The principal means which enable one to form a fairly accurate opinion about the age of an individual, especially in earlier years, are teeth, height and weight, ossification of bones and minor signs. Teeth.—The estimation of age from the teeth with some amount of certainty is only possible upto 22 to 25 years of age ; beyond that it is merely guess work. There are two sets of teeth, called temporary and permanent. The temporary teeth are also called deciduous or milk teeth and are twenty in number: four incisors, two canines, and four molars in each jaw. They appear in infancy, are shed in the course of a few years and are re- placed by the permanent teeth, which are thirty-two in number, consisting of four incisorSj two canines, four premolars or bicuspids, and six molars in each jaw. The following table shows the average periods of eruption of the tempo- rary and permanent teeth. Teeth. Temporary. Permanent. Central Incisors Lower Upper 6th to 8th month. 8th to 10th month. 7th to 8th year. Lateral Incisors Lower Upper 10th to 12th month. 7th to 9th month. 8th to 9th year. Canines 17fch to 18th month. llth to 12th year. Anterior Premolars or First Bicuspids Absent. 9th to 10th year. Posterior Premolars or Second Bicuspids Absent. 10th to 12th year. First Molars 12th to 14th month. 6th to 7th year. Second Molars 22nd to 24th month. 12th to 14th year.11 Third Molars or Wisdom Teeth Absent. 17th to 25tJi yea*,-^ -. From investigations carried out in schools of boy& and girls in Madras and Lahore, Shourie12 has prepared the following table showing the mean ages at which the permanent teeth erupt:— 11. In one ease I found that a boy, aged 15, had no second molar teeth. Dr. Sahay of Pataa reported to me that he examined two police recruits, aged 20 and 21 years res- pectively. Tite firs! of them had only twenty-three teeth. He had not cut the right tipper canine ^wtfe and the second molars. The second had only twenty-four teetit $$oaae of las seeoiast molars had eM^tecL Botfc. of ^iem were weH built and had no abnormality or <le$oiraity. 12. fed. J<mr. HeA B0m<V0L XX£?» No, 1, 194^ p. 105.