ELEPHANT AND MASTODON. 7 



successive fall and renewal of the teeth, from the youngest age up 

 to the adult, the periods of which he carefully recorded ; and 

 casualties supplied him with a series of upwards of thirty crania of 

 all ages, upon which he studied the form, size, and the number of 

 plates which enter into the composition of the grinders at different 

 stages of the animal's life. The observations embodied in this 

 memoir are the most valuable which have been made on the teeth 

 of either of the living species. Corse first showed that, the Indian 

 Elephant has ' milk' tusks (incisors) which cut the gum when the 

 calf is about six months old, but are extremely caducous, as they 

 drop out between the first and second year. He detected the 

 position of the capsule of the permanent tusks, which protrude 

 about two months after the milk incisors are shed, and go on 

 increasing in size during the rest of the Elephant's life. He has 

 described the variations in size, form, and direction which the 

 tusks present in the different sexes and castes of the Indian 

 species, the general character of which castes he has accurately 

 recorded ; but the most valuable part of his observations is com- 

 prised in what relates to the molar teeth. He showed that they are 

 reproduced several times during life, and that the number of 

 plates entering into the composition of each molar goes on 

 increasing as the teeth are successively renewed. This succession 

 he has carefully traced up to the fourth grinder ; the first cuts the 

 gum eight or ten days after birth, is well out at six weeks, and is 

 composed of four plates ; the second is completely in use at two 

 years, and consists of eight or nine plates ; the third serves the 

 period between the second and sixth year, and has twelve or 

 thirteen plates ; the fourth is in use between the sixth and tenth 

 year, and consists, according to Corse, of about fifteen plates. 

 Puzzled, probably, by the irregularity in the number of plates and 

 the size of the rest of the molars in different individuals, this faithful 

 observer stops short at the point where his observations ceased to be 

 conclusive, and does not attempt to define the number of plates in 

 those which follow after the fourth. He states, generally, that the 

 plates go on increasing successively up to the 'seventh or eighth set,' 

 when each grinder consists of twenty-two or twenty-three plates 



