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PROCEEDINGS OF THE NATIONAL. MUSEUM 



VOL. 66 



cavity the width of the band varies from 24 to 30 mm. On the 

 long fragment figured the width is 40 mm. Toward the distal end 

 the form of the section varies. This happens because of the wear 

 to which the ivory was subjected. On the whole inner face of the 

 long fragment the ivory is worn, the amount increasing toward the 

 distal end. This was produced probably by the friction of the 

 proboscis. A cross-section 100 mm. from the distal end is shown by 

 text-figure 6; another, 150 mm. from tip, by text-figure 7. The 

 lower border of this area of attrition comes down to the lower edge 

 of the enamel band, and thus was formed a sharp cutting instrument 

 ior a distance of nearly 250 mm. The distal end of the tusk is 

 likewise rounded off and polished. 



It is evident that the tusk was subjected to rougher usage than 

 friction by the proboscis. It will be seen (pi. 4, fig. 3) that along 



Figs. 8-9. — Gomphothe5Rium cimareonis. 8, Cross section of an upper tusk takejn 

 a short distance below the proximal end. the black center bjjpreisbnts the 



PULP cavity; THE BLACK BAND, THE ENAMEL. X .6. 9,. CROSS SECTION OF DISTAL END 

 OF LOWER JAW, SHOWING RIGHT AND LEFT RAMI AND THE RIGHT TUSK. X -57 



the upper edge of the enamel band and near the distal end are four 

 notches. Here the enamel had evidently had pieces broken out of it 

 as though it were glass. This had been done during the life of the 

 mastodon, for the broken edges are rounded off and from each notch 

 there runs a broad shallow groove in the ivory. These had probably 

 been j^roduced by play of roots or vines or branches of trees. Text- 

 figure 8 represents a cross-section of the upper left tusk near its 

 base. This tusk probably belonged to the same individual as did the 

 one just described. 



In the collection is a portion of the distal end of the lower jaw 

 containing a fragment 125 mm. long, of the right lower tusk. Text- 

 figure 9 represents a cross-section of this fragment of tusk and bone ; 

 and figure 4 of plate 4 is a reproduction of a photograph of the 

 broken end of the tusk. It will be seen that the two tusks were, as 

 in GomphotheriuTn productum^ separated by a bony septum. At the 

 rear of the fragment this septum is 7 mm. thick. It will be observed 



