11' Till- MAMMALIA. 



The first indications of teeth are met with at 

 a v. rv early >ta^e of the emhryo in the gums that 

 are still in tin- process of forming, and these be- 

 ginnings of teeth are then gradually enclosed by 

 the gums. In man and most of the other Mam- 

 malia during the lirst years of life we do not find 

 the whole set of teeth of their later years, of their 

 mature age, nor indeed any such teeth as are to 

 serve them throughout life ; there is at first a 

 temporary set of teeth, the so-called mill: tt:<-th. 

 These teeth are very like those that replace them 

 subsequently, the permanent teeth, but are smaller 

 and weaker. It was an extremely interesting and 

 important discovery when Eiitimeyer proved in 

 detail that the milk teeth of many of the Mammalia 

 >lmw a greater agreement with their historical i.a. 

 their geological ancestors than do the permanent 

 let- tli. As a rule, for instance, in man the first 

 f incisors, canine teeth, and front cheek- 

 i are replaced by a second set, and thus con- 

 st it ute the milk teeth. The teeth which replace the 

 milk rherk-t-'eth are called pr<' molars, and tlu-si- 



h cincr EnturickelungsgeschichU dcs 



-, 1882). This work may be recommended as an 



:ie on the subject and full of suggestive thoughts, 



:it times, feel disposed to dispute some of 



