249 



represented in Fig. 2, Plate XVII, of the Extinct Mammalian Fauna of 

 Dakota, &c, than it does those of Merychippus, represented in Figs. 5 and 9 of 

 Ihe same plate. On the other hand, it bears a near resemblance to the teeth 

 from Little White River, Dakota, represented in Fig. 1, Plate XXVII, of the 

 work just quoted, which were supposed to pertain to Merychippus mirabilis. 



Another specimen, from Bastrop County, Texas, consists of an upper molar 

 with the portion internal to the median enamel lakes broken away. It is 

 rather smaller than the preceding, and would appear to hold the relation with 

 it in the series of a fourth or fifth molar. 



A third specimen, accompanied by a label in the handwriting of Dr. Shu- 

 mard, is marked ("Eocene,) Trinity River, Navarro County, Texas." It is a 

 lower molar, represented in Fig. 20, Plate XX, and may perhaps belong to 

 the same species as the preceding. 



The measurements of the specimens are as follows: 



Linos. . 



Breadth of the second upper molar 9f 



Width of the second upper molar 10J 



Breadth of the fourth upper molar 8 



Breadth of the lower molar ... 9 



Width of the lower molar , . 5^ 



Fig. 17 represents a specimen found in association with those of Figs. 14, 

 15, at a depth of 25 feet, in Washington County, Texas. It is an upper 

 molar of the right side, probably the fourth of the series. It is but moder- 

 ately worn, and is imperfect at the back inner corner. In its proportions and 

 degree of curvature it agrees witli the teeth of Protohippus. In size and 

 arrangement of the enamel it approaches in character some of those referred 

 to Protohippus piacidus, represented in Figs. 39 to 48, Plate XVIII, of the 

 Extinct Mammalian Fauna of Dakota, &c. 



The measurements of the specimen are as follows : 



Lines. 



Length on inner side 8 



Length at antero-external corner 12 



Breadth of triturating surface , 7| 



Transverse diameter of surface 7 



Fig. 18 of the same plate represents a specimen from '"Little's Well," 30 

 feet in depth from the surface, in Bastrop County, Texas. It is a first upper 

 molar, and is sufficiently like the former to belong to the same species. It 

 32 g 



