FOSSIL HORSE. 



387 



Figure 143 shows the grinding surface of the third 

 molar, right side of the upper jaw, in a fossil from the 

 cave of Kent's Hole, Torquay. It presents the same fos- 

 silised condition as the bones and teeth of the extinct 

 Rhinoceros and the great Carnivora from the same de- 

 pository. The upper molars of the Horse are slightly 

 curved ; and a fossil species, contemporary with the Mega- 

 therium in South America, differs from the existing Horse 

 by the greater degree of that curvature : but there is no 

 such difference in the present fossil, which is of equal 

 length with a large Horse's tooth compared, viz., three 

 inches and a quarter ; neither is there any modification 

 of the pattern of the enamel folds on the grinding surface 

 deserving to be regarded as specific. This degree of dif- 

 ference is indicated only by the smaller transverse as com- 

 pared with the antero-posterior diameter ; and the same 

 difference of proportion, as compared with the teeth of 

 the common existing Horse, is shown in the figure of the 

 upper molar from the cave at Kirkdale, in the ' Reliquiae 

 Diluvianse," pi. vii., fig. 7. In general, I have found that 



Fig. 144. 



Fig. 145. 



3rd lower molar, recent horse, 

 Nat. size. 



3rd lower molar, Equus fossilis, Oreston, 

 Nat. size. 



the lower molar teeth of the fossil Equus present the 

 same difference in their narrower transverse diameter : 

 this character is shown in the cut of the grinding surface 



2c2 



