Jeffries on the Fingers of Birds. 
9 
Cyclopedia Owen cites Nitzsch as authority when stating that 
the claws at the radial side of the wing are supported by phalan- 
ges. (3) The argument from analogy to the foot is brought for- 
ward in the following words by Morse : “If we compare the leg 
and wing of Spizella we shall see that in this early stage there 
are but three metatarsals and three metacarpals, and it seems rea- 
sonable to compare them together. 
“ As the first toe appears much later and is reduced to two 
phalanges, and has its two metatarsals also greatly reduced, and 
as at the stage just cited the first toe is represented only by a few 
granules, it seems natural to infer that in the wing the first finger 
never makes its appearance.” Again Morse refers to the law of 
the reduction of digits. According to this law first the first and 
then the fifth digits are lost. 
If we examine these arguments it will be found that they can 
not now be held. First, the last remains of an Archceopteryx 
described by Vogt show no traces of the supposed thumb of Owen, 
though the specimen was very much better than Owen’s. The 
second argument, like the first, is without ground, and is not men- 
tioned in Owen’s Anatomy. The spurs found on the radial edge 
of the wings of certain birds are just like those found on the tar- 
sus of the cock and others of the same order. The bone within, 
if any, is a special development for support. These spurs are 
not to be confounded with the claws developed on the last pha- 
langes of the first and second fingers of many birds. 
In following the analogy of the hand to the foot among birds 
we must not forget the great diversity in their formations. Again, 
if we force the analogy at all, it becomes an argument in favor of 
the existence of I digit. In the hand we have four metacarpals 
developed, in the foot we have four, or more probably five ; the 
last, however, very rudimentary (a mere spot) , even in the em- 
bryo. Thus it seems more natural to omit the development of 
the little finger than the thumb. 
In considering the law of progressive reduction it must be 
borne in mind that this is the law as worked out among walking 
limbs, principally mammalian. Hence, with our present knowl- 
edge of the action of physical forces on life, it is a doubtful ques- 
tion whether the same laws would hold true for an organ used for 
such an utterly different purpose as the wing of a bird. In a 
walking limb the objects to be gained are: (1) The strongest 
