of Fingers and Toes, and of the Phalanges, in Man. 111 
in the case of the great toe, the distal end of whose meta- 
tarsal bone is the most developed. Comparative anatomy, 
however, sets this question at rest. I find that the distal 
position of an epiphysis on a metacarpal and metatarsal 
bone, and its proximal position on the phalanges, belongs to 
other mammalia as well as to man, and is adhered to not- 
withstanding the most varied proportionate size which the 
two kinds of bones, or their two ends, attain.* In the horse 
and ruminant, in which the great metacarpals and metatar- 
sals attain enormous size, they have still only one epiphysis, 
while the radius and humerus have an epiphysis at both 
ends; and the metacarpals and metatarsals have their epi- 
physis distal, while on the phalanges it is proximal. The 
short and flat thigh-bone of the seal has epiphyses at both 
ends, while the greatly elongated metacarpals, metatarsals, 
and phalanges, have but one epiphysis each, placed as on 
the corresponding bones in the human hand and foot. A 
still more striking example of this law is presented in the 
development of the rudimentary metacarpals and metatar- 
sals of the horse; the large upper ends of which, serving 
an articular function, are developed without an epiphysis, 
the epiphysis being kept for the little “ button ” which ter- 
minates the tapering lower end. The more we compare 
the muscles of the two limbs, and in the limbs of different 
animals, the less dependence do we place on their attach- 
ments for the determination of homology; and the above 
facts In comparative osteogeny show, that the position of 
the epiphysis is décisive in establishing the view that the 
bone which is wanting in the human thumb and great toe, 
and in the internal digit of other five-toed mammals, is the 
metacarpal and metatarsal, although custom and convenience 
lead us to apply these terms to the bone which homologi- 
cally is the proximal phalanx. 
* The cetacea present an exception to the mammalian law of three pha- 
langes, in the occurrence of more than three in the longer digits of the 
paddle, making an approach in this respect to the digital type of the fish. I 
have observed that the cetacean digits present another exception in the pre- 
sence of epiphyses at both ends of each phalanx, and also at both ends of the 
metacarpal bones. In contrast with this, we have the great distal phalanx of 
the horse, ruminant, pig, and some others, developed without an epiphysis, 
while in man it is present on the distal phalanx as well. 
