440 NATURAL SCIENCE. Dec, 



(radiale) just described, which he suggests may — if it have any 

 meaning at all — represent the boundary line between the radiale 

 and ulnare, so that after all we may be dealing, not with one, 

 but two bones, the homologues of the existing proximal carpals. As 

 to the probability of a distal row of carpal bones. Dames writes : 

 "There can be no doubt, speaking generally, that a distal row of 

 carpals was laid down (angelegt), since they are laid down in every 

 reptile, in every bird, indeed in every vertebrate, with the possible 

 exception of the fish ; and if this be admitted, the appearance of our 

 specimen shows that they must have fused with the metacarpals." The 

 nature of this view is next discussed. Quoting Rosenberg, he tells 

 us that in the embryo of living birds the carpals 1-2 appear from the 

 very first, not as separate elements, but as a single piece. Carpals 

 3-4 are similarly developed. The metacarpals^ first approximate 

 with their corresponding carpalia or their equivalents, and then fuse 

 with them and with one another ; but in Archaeopteryx, we are 

 reminded, these metacarpals are free : it is therefore open to question 

 whether (i) the development of these carpals in Archaeopteryx pro- 

 ceeded after this manner [i.e., as carpals 1-2 and 3-4) ; or (ii) as 

 carpals i and 2, 3 and 4 ; or (iii) whether the cartilaginous body, 

 which Rosenberg supposed to represent i and 2, really only cor- 

 responds to 2, in which case the first metacarpal would articulate, not 

 with a carpal of the distal, but of the proximal row — the radiale. 



Now if my reader will turn to p. 353, Fig. I., he will see 

 at a glance that Dames' interpretation of this region differs funda- 

 mentally from my own, inasmuch as what that writer believes to be 

 the radiale I imagine to represent a fused row of distal carpalia, 

 while the proximal carpals seem to me to be distinctly indicated, in 

 the photographs, in the space between this distal row and the end of 

 the forearm. On referring to the text, it will be seen that I have even 

 gone so far as to suggest the presence of an intermedium. Now, 

 supposing I am right, mark how much this matter will be simplified. 

 Turning again to p. 353, it will be seen that in Fig. II. — the wing of 

 the ostrich — we have precisely the arrangement of carpal bones that 

 I believe to have existed in Archaeopteryx, viz., two free proximal 

 carpals — perhaps three — and a fused row of distal carpals. The 

 difference between the two wings lies in tlie fact that in Archee- 

 opteryx the metacarpals- were probably distinct from one another 

 and from the distal carpal mass throughout hfe, whereas in the 

 ostrich they become anchylosed when the adult stage is attained. 

 Thus the carpus of Archaeopteryx represents neither the early 

 embryonic nor the adult stages of modern birds, but rather the late 

 embryonic and post-embryonic stages. Although my view of the 

 matter bears the stamp of probabihty, it cannot, of course, be ac- 

 cepted in any other light than that of a suggestion, and in this spirit 



2 Metacarpal IV. enjoys but a transitory existence. 



