DAKOTA AND NEBRASKA. 253 



1. An inferior last molar, from Madison, Indiana. It is worn throughout the 

 entire breadth, and measures fore and aft nine and three-quarter inches. It contains 

 twenty ridges, with a worn heel in front and behind, each of half an inch in thick- 

 ness. The widest ridge measures three inches. 



This specimen contains a greater number of ridges in the same space than any 

 other fossil Elephant tooth in the collection of the Academy. The crown is nearly 

 worn to its fangs, and yet the plates of dentine are thin. The plates of cementum 

 are still thinner, and the thin laminae of enamel are moderately crimped. 



It resembles very much a cast in plaster, in the Museum of the Academy, of a last 

 inferior molar of Elephas ivimigenius, the original of which, from the Canal de 

 rOurcq, near Paris, is represented in figure 6a, plate x, G. Elephas, of De Blainville's 

 Osteographie. The cast measures ten inches in breadth, and contains twenty-one and 

 a half ridges, with a prominence behind apparently composed of two more rudimental 

 ridges. The widest ridge measures three and a half inches. 



2. A superior last molar, nearly perfect, locality unknown, but with the aspect of 

 the Big-bone-lick specimens, measures thirteen inches in breadth, little more than 

 half of which is worn. It contains twenty-seven and a half ridges, of which the 

 widest is four and a half inches. The first unworn ridge or lobe is about eight inches 

 in length. 



3. A lower last molar with the anterior extremity broken off, of unknown locality, 

 but probably from Big-bone-lick. The triturating surface extends nearly the 

 breadth of the specimen, which is about eleven inches. It contains twenty-two divi- 

 sions or lobes, of which the widest is about three and a half inches. 



4. A lower last molar from Big-bone-lick. It is worn its entire breadth, and 

 measures ten and three-quarter inches. It contains twenty and a half ridges, of 

 which the widest is little over four inches. 



5. An upper last molar, probably from Big-bone-lick, a foot in breadth, which is 

 rather more than one-third worn. It contains twenty-five ridges, besides which it 

 has lost several of the more rudimental ones posteriorly. 



6. An upper last molar from Big-bone-lick, worn about two-thirds its breadth, and 

 broken at its fore part. The remainder measures ten and a half inches in breadth, 

 and contains seventeen ridges, of which the widest is four and a half inches. 



7. The anterior part of a molar, probably about half its original extent, from 

 Benton Co., Misssouri. It measures seven and three-quarter inches in breadth, and 

 contains twelve and a half divisions. 



8. An upper molar, from Willamette Valley, Oregon, worn rather more than half 



