402 



HIPPOPOTAMUS. 



Fig. 160. 



Structure 

 tamus 



tion. 



Fig. 161. 



inferior tusk of the Mastodon by 

 its partial investment of enamel, 

 or when this is lost, as in the 

 decayed specimen from the till at 

 Walton, by the fine concentric 

 lines on the fractured surface of 



; of ivory of Hippopo- ,1 //? -. f*r\\ ii 



tusk in transverse sec- the 1VO1 7 (% 160 )' the COrre - 



sponding surface in the tusk of 

 Mastodon presenting the decussating curvilinear striae as 



shown in fig. 101 c. The se- 

 cond specimen from Walton 

 is thus described by Mr. 

 Parkinson : " The point of 

 an inferior canine tooth or 

 tusk, measuring full nine 

 inches in circumference, and 

 having seven inches in length 

 of triturating surface (fig. 

 161). From the great size 

 of this tooth, it is very likely 

 to have belonged to the same 

 animal to which the preced- 

 ing tooth belonged. Be- 

 sides the longitudinal striae 

 and grooves observable in 

 the enamel of its sides and 

 End of lower tusk of Fossil Hippopota- inferior part, it is charac- 

 mus,*nat. s i Z e. Walton. terised by strong transverse 



rugous markings, which are placed at nearly regular dis- 

 tances of about two inches, and are observed to exist in 

 the same manner on the fragment which joins to it. 11 * 



* ' Organic Remains,' vol. iii., p. 375. In pi. xxi., fig. 1., there is a good 

 figure of the penultimate molar of the lower jaw of the fossil Hippopotamus from 

 Walton. 



