THE MASTODOX. 23 



oped, still larger in size. Before the appearance of the 

 fifth, and in most cases before the fourth shows itself, one 

 or more of the first teeth have disappeared. The sixth 

 and last tooth, which occupies the whole side of the jaw, 

 is much larger and different from any of the others. It is 

 about ten inches in length, four in breadth, twenty inches 

 around the neck, and weighing from ten to twelve pounds. 

 The crown is divided into four or five ridges, with its eight 

 or ten points and furrows more deeply cleft than in the 

 other teeth, and the ridges larger and broader. A supple- 

 mentary, or seventh tooth, was discovered in Michigan in 

 1854. It has the general characteristics of the fifth tooth 

 of the M. giganteus. 



This succession of teeth w^as necessary, because the ani- 

 mal required great quantities of food, and the prodigious 

 labor imposed upon the molars could only have resulted 

 in impairing the tooth, and the molar, thus employed in 

 crushing and bruising the coarse vegetable substances, 

 gradually Avore out both in thickness and length. During 

 this wearing and wasting away, another is developed, 

 which pushes the active tooth before, in the direction 

 of the length of the jaw. By this method the old root is 

 broken and soon the tooth gives way, making room for the 

 newer and stronger one. 



It should be noted that in the if. angustidens and M. lon- 

 girostris there is an additional pre-molar tooth situated at 

 the root of the second milk-tooth. 



YII. FOOD. 



The contents of the stomach of the Newburgh mastodon 

 were described by Dr. Prime, as follows : " In the midst 

 of the ribs, embedded in the marl and unmixed with 

 shells or carbonate of lime, was a mass of matter composed 

 principally of the twigs of trees broken into pieces of about 

 two inches m length, and varying in size from very small 



