324 STRUCTURE AND ADAPTATION OF TEETH 



localities; as in tlie superficial beds overlying the 

 chalk on the coast of Kent, and especially in the 

 tertiary strata known as the " Norfolk Crag." 

 The specimens on the table, from the latter forma- 

 tion, supply another illustration of the immea- 

 surably long periods which have elapsed since this 

 comparatively recent geological epoch. One of 

 the teeth, imbedded in a cliff of compact strata, is 

 as sharp in its outlines as at the animaFs death ; 

 while the other specimens have been rolled into 

 boulders by the action of the sea on that more 

 ancient cliff, and yet the gravel bed itself contain- 

 ing these remains was raised, long before the 

 human period, far above the present level of the 

 ocean. The tusks of the extinct European ele- 

 phant are very much more curved than those of 

 the existing species, and sometimes are found with 

 a curvature almost equalling that of the ram's 

 horn. The tusks are so numerous in Siberia, and 

 are in such excellent preservation, that they form 

 an article of extensive commerce as ivory. Per- 

 haps few discoveries of the remains of an extinct 

 animal have equalled in interest the fossil elephant, 

 which was found frozen up in an icy tomb on the 

 coast of Siberia. In the year 1799, a Tungusian 

 fisherman observed a strange, shapeless mass pro- 

 jecting from an ice- cliff, near the mouth of the river 

 Lena, in the north of Siberia, the nature of which 

 he did not understand, and which was so high as 

 to be beyond his reach. In consequence of the 



