Geological Society. 135 



tooth is gradually pushed forward, and rises as the fangs are added, 

 according to the demand occasioned by the abrasion of the exposed 

 crown, and the consequent absorption of the anterior fang; the posterior 

 part of the tooth not having yet cut the gum, while the anterior portion 

 is completely worn away. Before it are seen the relics of the preceding 

 tooth, the place of which the tooth in use was progressively supplying. 



The lower jaw in this species is less square and deeper than it is in 

 M. giganteum. 



The tusks, judging from the alveoli, must have been of equal volume 

 with those of the largest living Elephant. 



The following is the measurement of some of the remains of M. 

 latidens. 



Extreme breadth of fragment of cranium (upper jaw with 



the greatest part of both grinders) • . . . . IFt. 3In. 



Length of ditto 1 8 



Extreme length of right anterior grinder (6 denticuli and 



the spur) 8^ 



Extreme breadth at third denticulus 4 



Circumference of lower jaw, measured over the grinding 



surface of the tooth 2 4 



Extreme length of tooth llf 



Extreme breadth 4A 



Circumference of the lower extremity of right femur. . . 2 2 



Same, round the condyles 2 4 



Mastodon elephantoides. — M. dentibus latis; denticulis numerosis, 

 compressis. 



This species must have been smaller than the last. There is a fine 

 example of the lower jaw, showing the tooth in the highest degree of 

 perfection. The tooth is 1 1 inches long and 3^ inches broad, has no 

 less than ten denticules, and each of these denticules is mamillated with 

 small points; five being the smallest, and eight the greatest number on 

 any one denticule. In front of this tooth is seen the remnant of the pre- 

 ceding one, worn down and disappearing; and behind it is the cavity 

 wherein the young tooth, intended as a successor to that in existence, 

 was in the course of formation. The denticules are much more com- 

 pressed than those in the species last described ; they are closer together. 



