THE HORSE OF THE PRESENT AND THE PAST 477 



animal belonged to the odd-toed or even-toed group, and it will shortly 

 appear that it is most essential that there should be no I'isk of error in 

 the conclusion arrived at. 



It will be seen by referring to fig. 654 that there is a marked 

 difference in the arrangement of the digits in the two figures in the 

 diagram. In the first figure, a, which may be taken to represent the 

 foot of an early ancestor of the horse, the five digits are shown. The 

 shaded parts are the bones which are to Ije found in the horse now 

 existing. The special feature of the pe7'issodactyIe or odd-toed animal is 

 the one large middle digit, the third in situation. In the next figure, 

 B, representing the foot of the ox, the plan of construction is that of 

 the artiodactyle or even-toed group. The first digit is not present, even 

 in the most ancient members of the group, the second and fifth are 

 absent or rudimentary in the recent members, and instead of one large 

 middle digit there are two of equal size. These are distinct, and form 

 the so-called cloven hoof of the ox, which is, in fact, constituted of the 

 two middle digits, the third and fourth in situation. The shaded parts of 

 the bones in the second and fifth digits in the diagram show the portions 

 which remain in the foot of the ox. 



Even a tyro in the science of anatomy will be able to understand 

 the value of the indications afforded by the middle digit . or digits in 

 assigning to the animal to which they belong its proper jDosition in the 

 order Ungulata. For further illustration it may be assumed that the 

 bones of the foot of an imaginary animal are in c^uestion, and it is 

 granted that the animal is an ungulate mammal, and must therefore 

 belong to the odd-toed or even-toed group. To determine which, the 

 enquirer proceeds to examine the bones of the extremities below the 

 carpus or wrist, otherwise called the knee, and the tarsus or heel, 

 known as the hock in quadrupeds. Finding below these joints one large 

 digit, no matter what other bones are present or absent, it is at once 

 decided that the animal is one of the jierissodactyle or odd-toed mammals. 

 If, however, there are two equal digits, it is as certain that the animal 

 is one of the artiodactyle or even-toed mammals. 



Applying this scheme to the horse, it will be evident that as there 

 is " one big digit ", consisting of four phalanges extending from the knee 

 or hock to the toe, on the hoof-covered tip of which the horse stands, 

 the animal must be classed with the perissodactyles or odd-toed, and also 

 with the Solidungula or single-hoofed mammals. 



Attached to the back of the one big digit of the horse, the leg-bone, 

 cannon or shank hone as it is sometimes called, are the well-known 

 sp/m^bones, one on each side, reaching from the knee or hock to a point 



Vol. ni. " 96 



