AND THE PROBLEM OK DIAST ATAXY. 
313 
The Bird’s wing is in itself an exceedingly interesting organ, 
viewed from an evolutionary point of view; and I have, therefore, 
commenced this paper with a brief summary of its salient features, 
designed to stimulate an interest in the subject, as well as to help 
those not already familiar therewith An appreciation of the 
general morphology of the wing is certainly necessary to those 
who intend entering the lists of the great puzzle competition : 
What is diastataxy 1 
A glance at the skeleton of the wing of an adult of any of our 
common birds will be sufficient to convince the trained observer 
that it is a highly specialized structure, built up by a process of 
slow transformation from some originally ainbulatorial fore-limb. 
His ground for such a conclusion will be the fact that the carpus, 
or wrist, contains but two free elements, whilst the metacarpal 
bones and phalanges have obviously undergone great changes and 
modifications, thus rendering the limb, as a whole, an unique 
Fig. 1. 
Fig. 1. The manus or hand of a young Itliea, showing the separate 
elements of the wrist joint, and the distinctness of the bones of the hand, 
r and u represent the portions of the radius and ulna, the bones of the 
fore-arm. V' and u" the carpal or wrist bones of the proximal or inner 
row, known as the radiale and ulnare. D.c is the mass of fused wrist bones 
described in the text. Originally there were three separate elements— one 
for each metacarpal bone. The three now fuse together to form what is 
known as the distal — or meta — carpal mass. Ultimately this mass fuses 
with the metacarpal bones, and undergoes slight changes of form so that 
all trace of the distinctness which obtains in the nestling is lost. Compare 
this figure with the skeleton (Fig. 3) on page 317, representing an adult 
wing of a Hawk. 
