EXPLANATION OF PLATE V. 



All the figures of the natural size except Fig. 11, -which is one-half the size. 



rigs. 1-3 Trogosu.s castoridens. A lower jaw, discovered iu the vicinity of Fort Bridger by Dr. 



Carter. 

 Fig. 1. View of the left ramus of the jaw. 

 Fig. 2. Triturating surface of the second true molar, much worn. The other molars are too 



much injured to ho characteristic. 

 Fig. 3. Front view of the jaw, exhibiting the large rodent-like incisors. 



Figs. 4-11. Pal^osyops paludosus : 



Fig. 4. An upper last premolar, the triturating surface much worn. From Henry's Fork. 

 Hayden's collection. 



Fig. 5. An upper last premolar, nearly unworn. This is one of the original specimens upon 

 ■which the genus and species were established. From Church Buttes. Hayden's collec- 

 tion of 1870. 



Fig. 6. Outer view of a last upxier molar, left side. Henry's Fork. Hayden's collection 

 of 1870. 



Fig. 7. Triturating surface of the same specimen ; the outer fore-part much fissured, with 

 the i)ortions displaced and the single inner lobe partially broken away. 



Fig. 8. Outer view of a second njiper molar, from the opj)Osite side of the same individual. 



Fig. 9. The triturating surface, with the outer lobqs much worn. Figs. 6-9 are from 

 specimens, which were attributed to the same species at the time of the original uotice of 

 it in the Proceedings of the Academy of National Sciences, Philadelphia, 1870, p. 113. 



Fig. 10. View of the triturating surfaces of the last two premolars and the molars from the 

 specimen represented in the next figure. 



Fig. 11. Left ramus of a lower jaw, containing the teeth just indicated. This fine specimen 

 was discovered by Dr. Carter thirteen miles southeast of Fort Bridger. 



