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 : "Tf 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 Archceofiteryx 

 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 probablv 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 phvsical 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 



