On the Milk Dentition of Orycteropus. 383 



distinct but obtuse point. The third milk premolar is situated 

 9 mm. behind the second. It is also broad and obtusely pointed, 

 but less than 1 mm. in antero-posterior length. The fourth milk 

 premolar, which lies about G mm. behind the third, is relatively 

 of large size, measuring about 1^ mm. in antero-posterior length. 

 It appears to have some indications of two roots. About 3 mm. 

 behind it is a very small fifth milk premolar, and 7 mm. behind the 

 fifth is a fairly large sixth milk premolar which has an antero- 

 posterior measurement of 2 mm. 



Underneath the third milk premolar there is apparently a minute 

 permanent tooth developing, but it is not yet calcified. Under the 

 fourth milk premolar is a calcified permanent tooth of about equal 

 size. Partly under but mainly behind the small fifth milk premolar 

 is a large developing permanent tooth, which has an antero-posterior 

 measurement of between 4 and 5 mm. Under the sixth milk pre- 

 molar is a permanent tooth rather smaller than that in front of it. 

 There is evidence of at least four other teeth of the permanent 

 set behind the sixth milk premolar. 



In the lower jaw there are also three milk incisors, all of which 

 are very small, but all calcified. The first lies near the front of the 

 jaw and about 2 mm. from the symphysis. The third is 6 mm. 

 behind the first, and the second between the others but nearer to the 

 third. About 4-7 mm. behind the di3 is a very minute canine. 

 When the jaw is in position this canine lies a little in front of the 

 upper milk canine. 



About 5 mm. behind the canine is a rather larger tooth, doubtless 

 dp'. 5"5 mm. behind this is the second milk premolar. This dp^ is 

 a pointed flattened tooth directed somewhat forwards. It has an 

 antero-posterior measurement of nearly 1 mm. About 8 mm. further 

 back is situated dp3, a tooth nearly similar in size and shape. The 

 fourth milk premolar is about 3 mm. behind dps. It is appreciably 

 longer than the anterior teeth, but not much wider. It has a distinct 

 pulp cavity. About 2i mm. behind it is a smaller obtusely pointed 

 dp5. And 6 mm. behind dps is a large dp^. This last tooth is the 

 only milk tooth in the lower jaw of fairly large size. It measures 

 a little over 1^ mm. in antero-posterior length. 



Immediately behind dp= a developing permanent tooth can be 

 seen, and between dp3 and dp4 a second permanent tooth. Between 

 dp-* and dps there seems to be a third, but it is not very distinctly 

 seen. Immediately behind dps is a large pointed permanent tooth, 

 and below dp^ is a developing fifth permanent tooth. Behind this 

 there are evidences of apparently three other permanent teeth. 



