208 Mr. R. Walker on Clays containing Fossils. 



from the heretofore recognized characters of the last tooth of 

 that species in having a bilobed posterior termination, apparently 

 agreeing in this respect with the last molar of E. plicidens ; 

 the enamel and dentine folds, however, extend across the crown, 

 like those of the last molar of E. fossilis as figured in the ' Fossil 

 Mammals/ It has been observed by Prof. Owen long ago, that 

 the fossil horse had proportionally a larger head than obtains in 

 the domesticated races. While this is, no doubt, the case to a 

 considerable degree, still, were we to assume that the fossil horse 

 had as large a head as the recent, in proportion to the size of 

 the molar teeth (which, in the case of the former, are often found 

 detached), we should be somewhat mistaken. At least, in the 

 fossil under consideration, the majority of the teeth are nearly 

 as large as the teeth of the cart-horse of the present time, while 

 the head itself has evidently been a good deal less. However, 

 to show the relative sizes more clearly, I will, as far as practi- 

 cable, give the measurements of the fossil cranium, the molar 

 teeth, and the tibia, together with similar measurements of a 

 Scottish pony and a cart-horse, the latter appearing to me to 

 be a fair representative of its class : — 



Length of the intermaxillary bone (measured g^j^jji^jj (>^_ 



over the curve) from the edge of the alveo- pony. Fosfii. horse. 



lar cavity of the first or middle incisor to inches, inches, inches. 



the termination of the ascending apophyses 7^ 8^ 9| 

 From the anterior edge, in front of the canine 



tooth of the superior maxillary, in a straight 



line to the orbital cavity 9f 10^ 12^ 



Breadth of the superior maxillary, from the 



anterior edge of the first molar to the upper 



edge, at the poiut where the intermaxillary 



bone terminates 3| 4| 4| 



Dimensions of the molar teeth. 



Antero-posterior diameter of the crown of the 



first molar 1 1 1| 1^ 



Antero-posterior diameter of second molar. .1 1^^ 1^ 



» „ third molar . . i-^ 1^ 1^ 



„ „ fourth molar . . |-j^ 1 1^ 



.. „ fifth molar. . . . ^-^ 1^ 1 A 



» „ sixth molar .. 1-j^ 1^ mtV 



Dimensions of tibia. t t t 

 Extreme length, including tibial spine or 



central process in the knee-joint 13^ 13| 16 



Greatest transverse diameter of the head . . 3f 3f 4i 



» „ ofthe distal end 3 2| 3| 



Least circumference of the shaft 4| 4|. 6^ 



