163 



Judging from the conditions depicted in Plato 111, the month 

 at eight years of age is somewhat varying in its degree o£ 

 forwardness. The secondary intermediates and corner incisors 

 show little wear at this time, the Literals and centrals look very 

 broad and their thin nipping edges slant obliquely outwards and 

 backwards whereby the incisor line gets somewhat a serrated 

 appearance ; centrally it is sharp and prominent, laterally where 

 the central and primary intermediates meet it is grooved by 

 the rubbing of hard stalks, thus results at the inner edge of each 

 primary intermediate a prominence. So the incisor line gets a 

 very irregular ugly look. 



The mouth in full wear at nine years of age has a fine show of 

 good working teeth all a little worn but not sufficiently so to in 

 any way impair efficiency. The incisors mutually support one 

 another and form a rough nipping margin. The lower tush in 

 the particular instance figured has become curiously grooved 

 behind in the form of wear peculiar to camel's teeth and due, no 

 doubt, to the method of browsing adopted by these ruminants 

 (Plates VI and VII). 



At fen years of age the wear is a little more marked (J, Plate 

 VII). 



After this we find increased wear of each of the teeth until 

 the condition shown in Plate VIII is attained. Here the 

 organs are still in good working order, they are upright, 

 firm in the jaw, worn to rounded tables on which in the 

 incisors slight secondary dentine marks may be noted. The 

 incisors still mutually support one another and the upper incisor 

 meets the lower corner incisor and they form tables by mutual 

 friction. The lower tush is not much worn. 



A full mouth of permanent teeth as compared with a full mouth 

 of temporary front teeth can be studied in Plate III, figs. F and 

 G. The smallness, light build, and narrowaiess of the milk incisors 

 is very evident ; they meet in front at an acute angle, and thus 

 such a mouth as F, can only by the veriest tyro be mistaken for G, 

 much less for the fine array of stout old teeth shown at VIII, I. 

 To make assurance doubly sure we find in the two year old mouth 

 no anterior tooth in tho upper jaw except a few rudinionts. 



