i894. ^^^ WING OF ARCH^OPTERYX. 445 



that I have already shown this to be more than probable, and it 

 remains for my readers to decide whether I am right, or whether, 

 with Dr. Hurst, we are to regard these digits as too " weak-jointed''' to 

 bear the " torsional stress " to which they would be subjected. 



As to the slenderness of the digits, I have already pointed out 

 that relatively to the size of the wing they are not more slender than 

 is the case in living birds ; further, in so far as the metacarpals are 

 concerned, that of digit III. is stouter than obtains to-day. The 

 wing of the young ostrich presents an interesting exception (see p. 

 353, Fig. II). Here metacarpal III. is a relatively stout bone, as in 

 Archaeopteryx, but differs therefrom in being more bowed. Indeed 

 this wing seems to represent a stage in the evolution of the avian 

 manus between those of Archaeopteryx and modern Carinatai, since 

 it possesses a fused mass of distal matecarpals, approximated to, but 

 not fused with the three free metacarpals, and since all its digits end 

 in a claw. Another stage is afforded by those birds that have the 

 third metacarpal reduced to a slender bar, and only digits I. and II. 

 ending in a claw ; while in the highest birds even the claws are 

 lost. As both Professor Fiirbringer and Dr. Gadow have already 

 shown, it is very evident that the ancestral ostrich must have pos- 

 sessed the power of active flight, and this power must therefore have 

 been acquired while the metacarpals were yet free, as in Archae- 

 opteryx. Thus, then, we have a chain of connecting links between 

 the wing of this ancient fossil and those of the highest living birds. 



The weak-jointedness of the phalanges hardly need detain us long, 

 inasmuch as, so far as I can see, the phalanges of living birds seem 

 to be scarcely if at all more firmly bound together than were those of 

 Archaeopteryx ; indeed, remembering the strong tendinous fibres and 

 bands which bind together both skeleton and the supported remiges, 

 any special mechanism or anchylosis of the joints would seem to 

 be unnecessary. The presence of the digits which supported the 

 primaries. Dr. Hurst tells us, is indicated on the slab by a " shadow 

 which runs parallel with and behind the slender digits." Among some 

 notes on the subject taken in Berlin, which Dr. Hurst has generously 

 furnished me with, I find the following reference to these digits and 

 the shadow : — "Supposed position of IV. and V. wrong! Supposed 

 shadow is a yellow stain — ? iron, and the supposed IV. and V. if present 

 are completely hidden." This last qualification, " if present," looks 

 very like a doubt and but for the fact that in a letter lately to hand 

 he says " I do not in the least think that what you brought forward 

 at Oxford weakens my case," I should have believed that he had 

 surrendered his position, and therefore have considerably curtailed 

 my review of his paper. 



Yet a few more words remain to be said as to these additional 

 fingers. Supposing them to exist, where did they articulate ? The 

 whole of the carpal space is evidently monopolised by the " three 

 free digits," so that there seems no room for two, or even one more 



o 



