EXPLANATION OF THE PLATES. 



in situ. Parts of the broken posterior molar teeth are seen below the anterior 

 molar teeth on either side. The plate is on the scale of half an inch to an inch. 



Measurement. Ft. In. 



Extreme length of the portion of skull 18 



Extreme breadth of the same IS 



Circumference of the alveolar cavity of the tusk, calculated from 



the remains of the cavity 16 



Extreme length of right anterior grinder (six denticuli and the 



spur) 8| 



Extreme breadth (at the third denticulus) 4 



Breadth of the palate (about the middle) Sf 



Plate XXXVII. 



Fig. 1. The palate, and molar teeth of the right side of Mastodon latidens (a younger 

 animal than the last). The anterior tooth is very much worn. The anterior 

 part of the posterior tooth appears to have been just brought into use. This 

 tisrure is of the natural size. 



Figs. 2 to 4. Fragments of molar teeth of Mastodon latidens, showing the surfaces ac- 

 cording to the effects of mastication ; on a scale of half an inch to an inch. 



Plate XXXVIII. 



Fig. I. Fragment of the anterior part of the right side of the lower jaw of Mastodon 

 latidens seen from above. A string passed round this fragment, over the anterior 

 part of the grinder where it is worn, measured two feet four inches. Extreme 

 length of the tooth eleven inches and three quarters. Extreme breadth four inches 

 and a half. 



Fig. 2. Left side of the lower jaw of Mastodon elephantoides. The remains of the 

 anterior molar tooth are seen, and behind it, the posterior tooth which was advan- 

 cing, and which, in consequence of the jaw-bone being broken away, is seen 

 through its whole length. This tooth is eleven inches long and three and a half 

 broad. These two figures are on a scale of half an inch to an inch*. 



* It may not be uninteresting to give the measurement of the molar teeth of some recent and 

 fossil Elephants in the Museum of the College of Surgeons by way of comparison. 



Recent. 



Ft. In. 



African elephant. Longest grinding surface (lower jaw) 9 



Breadth of the same 3 



Asiatic (an old animal). Longest grinding surface (upper jaw) . . . 7^ 



