of Fingers and Toes, and of the Phalanges, in Man. 109 
the thumb to be the first, teleologically considered, the last, 
to suffer reduction. 
Increase in the number of phalanges occurs in the thumb 
only, or as in cases 17 and 17(a), in the digit serially cor- 
responding to the thumb when six digits are present. None 
of the cases presented a higher number than three, the full 
number in the mammalian type. Case 26, in which, with- 
out any increase in the number of the digits, the thumb 
presents an additional phalanx, is a very remarkable one 
when we consider the mammalian law. Not unlikely, it 
may have been the same in the father of cases 17 and 
17 (a), who is described as having had very long thumbs, 
while his son and daughter had three phalanges in the 
corresponding digit, and a thumb with two phalanges added 
by its side. 
On the absence of a Bone in the Thumb and great Toe, as 
compared with the other Digits ; and on the Nature of 
the ‘ Metacarpal” or ‘“‘ Metatarsal” Bone of the Inter- 
nal Digit. 
The occurrence, normally, of a bone less in the thumb or 
great toe than in the other digits, is part of a law exempli- 
fied in the inner digit of all five-toed mammals,* and may 
be supposed to find its explanation in the fact that the in- 
ternal is the small toe, and the one which has disappeared 
when the number is reduced to four. Whatever be its 
meaning, this law is maintained in the few cases in which 
the internal digit undergoes great teleological development, 
as in the seal and walrus,t in which the internal digit is 
longer and thicker than the three middle digits, and in 
* This law is not without exception in cases of variation, as in case 26; 
and I have lately been presented by Mr Robertson of Kelso with a pig’s foot, 
presenting five toes, in each of which there are three phalanges besides the 
metacarpal bone. 
+ I have seen a skeleton of the walrus with three phalanges in the pollex, 
but on trying with my penknife, I found one of them to be a piece of wood. 
In the skeleton of a seal I once saw three natural phalanges in the inner 
digit, but the first and fifth toes had been transposed. The phalanges and 
metacarpals and metatarsals of the seal are arranged and developed exactly as 
in man, and the presence of only two phalanges in the pollex and hallux is 
easily felt in the living seal. 
