188 
ON THE ERGOT OF EQUIDAE 
tlic after claws of cattle. This was the development in the case of the Un- 
yulata, but with the Peristiclactira the first finger was rudimented, then the 
fifth, fourth and second in order. That the fourth finger was rudimented 
earlier than the second may be seen from the splint bones of the present 
Iü]uidae, because the inner splint bone is always larger and longer than the 
outer. P'rom this fact I infer that the Callosity is the nail of the second toe 
and the Krgoet of the fourth toe. But when the present position of the Callo- 
sity and lu'got is observed it appears to be a curious place for a nail to grow. 
To that I will answer that in a perfect finger the nail should be at the tip, but 
in the case of a rudimented finger there is no connection between the finger 
bone and the nail. A good example of this may be seen in the nail of the 
first finger of the hind foot of a dog, the position of which has so greatly 
altered. In particular, when the finger bone has no function as finger and the 
nail is still of use to its possessor, the latter always remains in a useful posi- 
tion, and the bone only is rudimented. From this fact, with the Equidae, as 
the second and fourth fingers only were rudimented, the nail of the fourth 
finger, the Ergot, v/as of use, like the after claw of cattle ; the nail of the 
second finger of the foot remained as a means of attack, and it can be seen that 
when a horse fought with its enemy, hugging him with the fore feet, the 
Callosity might have been a useful weapon. 
From the above morphological and histological results it is not to be 
believed that the Callosity and Ergot which present Equidae bear are, as 
Zietzmann and other zoologists state, rudimentary pads, and I must affirm 
that they are rudimentary digits. 
