372 IVORY AND THE ELEPHANT 



inches of bone, the surface is soaked with thin shellac. 

 When dry this imparts surprising hardness. The surface 

 is then covered with strips of shellacked rice paper, or with 

 strong paper or cloth dipped in plaster of Paris. This sets 

 at once and a fresh surface is exposed and treated in a like 

 manner. The whole is then "cinched" or bound with 

 strips of gunny sack dipped in plaster of Paris. This stony 

 covering is so protective that bones may be shipped in en- 

 tire safety to the laboratory. 



The tusks of early mastodons are instantly recognized 

 by a longitudinal band of enamel. This band, about 1 to 

 2 in. broad in the earlier Nebraska mastodons, began to 

 decrease in width until it was scarcely a quarter of an inch 

 wide in Tetrabelodon willistoni. In Eubelodon morrilli and 

 Mammut americanvm it had disappeared altogether. It 

 is said, however, that a bit of enamel still persists as an in- 

 teresting vestige on the tips of the young of living elephants, 

 but this is soon worn off. 



In all fossil tusks the structure and decussations are 

 like that of modern ivory. . Sometimes the tusks are as 

 pure and white as ivory itself, but do not possess its strength. 

 Due to mineralization, they may be hard, and occasionally 

 dark in colour, though generally gray. In rare instances 

 tusks are silicified. In one instance a portion of a mammoth 

 tusk from Brown County was converted into that variety of 

 mineral known as odontolite, or "bone turquoise." Three 

 beautiful gems were cut from this material. 



As compared with living elephants, the early Nebraska 

 mastodons had proportionally longer bodies and necks, 

 but noticeably shorter limbs. Their successors, the mam- 

 moths, had compact, short bodies and necks, and long pillar- 

 Uke limbs. The most striking difference between our early 

 and late Nebraska elephants lies in the long skulls and jaws 

 of the former and the short skulls and jaws of the latter. 



