288 THE POPULAR SCIENCE MONTHLY. 



am now showing you is separable from the rest, and only unites as 

 the animal becomes older, and this is, in point of fact, the lower ex- 

 tremity of the ulna ; so that we may say that in the horse the middle 

 pai*t of the ulna becomes rudimentary and unites with the radius, and 

 that the lower extremity of the ulna is so early united with the lower 

 extremity of the radius that every distinct trace of separation has 

 vanished in the adult. 



I need not trouble you with the structure of this portion that 

 answers to the wrist, nor with a more full description of the singular 

 peculiarities of the part, because we can do without them for the 

 present, but I will go on to a consideration of the remarkable series 

 of bones which terminates the fore-limb. We have one continuous 

 series in the middle line which terminates in the coffin-bone of the 

 horse upon which the weight of the fore-part of the body is sup- 

 ported. This series answers to a finger of my hand, and there are 

 good reasons perfectly valid and convincing reasons, which I need 

 not stay to trouble you with which prove that this answers to the 

 third finger of my hand enormously enlarged. 



And it looks at first as if there were only this one finger in the 

 horse's foot. But, if I turn the skeleton round, I find on each side a 

 bone shaped like a splint, broad at the upper and narrow at the lower 

 end, one on each side. And those bones are obviously and plainly 

 and can be readily shown to be the rudiments of the bones which I 

 am now touching in my own hand the metacarpal bones of the sec- 

 ond and of the fourth finger so that we may say that in the horse's 

 fore-limb the radius and ulna are fused together, that the middle part 

 of the ulna is excessively narrow, and that the foot is reduced to the 

 single middle fingei*, with rudiments of the two other fingers, one on 

 each side of it. Those facts are represented in the diagram I now 

 show you of the recent horse. Here is the fore-limb (pointing to the 

 diagram), with the metacarpal bones and the little splint-bones, one 

 on each side. It sometimes happens that by way of a monstrosity 

 you may have an existing horse with one or other of these toes that 

 is, provided with its terminal joints. 



Let me now point out to you what are the characteristics of the 

 hind-limb. This (pointing to the diagram) is the shin-bone of the 

 horse, and it appears at first to constitute the whole of the leg. But 

 there is a little splint at this point which is the rudiment of the small 

 bone of the leg what is called the fibula and then there is con- 

 nected with the lower end of the tibia a little nodule which represents 

 the lower end of the fibula, in just the same way as that little nodule 

 in the fore-limb represents the lower end of the ulna. So that in the 

 leg we have a modification of the same character as that which exists 

 in the fore-limb the suppression of the greater part of the small 

 bone of the leg and the union of its lower end with the tibia. So, 

 again, we find the same thing if we turn to the remainder of the leg. 



