SCHIN, YOSCHIDA igj 
How is it that such a peculiarity should have arisen among Kquidae ? 
To account for it I will first write of the Callosity. That the Callosity 
is a rudimentary nail from its histological structures, and the reason of its 
being found either on the fore feet only or when on both fore and hind feet 
larger on the former than on the latter, I have already explained, but will 
now briefly repeat. 
When the digits of different Mammalia are observed, it is found with a 
few exceptions that when the number on the fore and hind limbs is different, 
this is always greater on the fore than on the hind limbs, and that when fore 
and hind limbs have the same number, those on the fore limbs are always 
more developed than those on the hind. 
Man and the man-like apes have five perfect digits on all four extremi- 
ties, but those on the hind limbs are smaller than those on the fore. 
Among dogs, five toes are found on the fore legs and four only on the 
hind legs, sometimes with a fully developed fifth. 
Cattle have four toes on the fore and hind feet, with two degenerated so- 
called after-claws. 
Tapirs have four toes on the fore feet and three on the hind feet. 
Parameles have three toes on the fore feet with rudimentary first and 
fifth, on the hind feet two toes with rudimentary first, second and third. 
The Equidae have one toe on both fore and hind legs. 
Why is there this difference between the digits of the fore and hind 
limbs ? 
The fingers of the fore extremities serve to take up nourishment and for 
purposes of suckling, while those of the hind extremities are only used to 
support the body or for movement, and therefore they need to be more develop- 
ed on the fore than on the hind limbs. 
When we observe the many specimens in the Natural History Depart- 
ment of the British Museum, and if we believe the theory of English natural- 
ists of the development of the Equidae, we can understand that the Callosity, 
which from its histological structure is a rudimentary digit, is always more 
