318 MR. W. P. PYCRAFT ON THE BIRD’S WING 
wings of the Bat and the Pterodactyle on the one hand, and 
the bird on the other, lies in the fact that in the two former 
it is formed by a sheet of membrane; whilst in the latter (Fig. 3) 
the membrane is almost entirely replaced by isolated, overlapping, 
ribbon-shaped plates of complex structure, known as the quill 
feathers or remiges. The wing membranes of the former are , 
however, represented in the bird, as will be seen by a reference 
to Fig. 3. It has been suggested, and the suggestion is by no 
means improbable, that these were once of much greater extent, 
and served the purposes of flight. Both the upper and under 
surfaces of these membranes, it is supposed, were scale-covered, 
and, it is further suggested, that the scales, by a gradual increase 
in size, have given rise eventually, by slow transformation, to 
feathers. The gradual development of these, from the primitive, 
original scales, was followed by an equally gradual degeneration 
in the size of the primitive wing membrane, — the membrane 
diminishing as the developing feathers became more efficient — 
till the form and proportions of the existing wing have been 
reached. 
This brings us to the second part of our theme— the arrange- 
ment of the wing-feathers of living birds. 
This subject has received much attention, several memoirs having 
been devoted thereto. 
Any one who will open out the wing of a freshly-killed bird, 
and examine it closely, will notice that the feathers thereof overlap 
one another after the fashion of tiles upon a roof, or, a still better 
comparison, of scales upon a fish or reptile. A comparison of several 
wings of different species of birds would furthermore show that, 
though all agree in the method of the overlap of the remiges and 
the row of coverts immediately above them, yet very distinct 
differences in this overlap obtained in certain of the rows beyond 
these. Thus, for instance, in the wing of the Little Stint, 
Fig. 4, the overlap of the remiges, the row of coverts resting upon 
them, and numerous rows of small feathers lying along the anterior 
border of the wing is distal. That is to say, the free edge of the 
vane of the feather is turned away from the body, or towards the 
tip of the wing : whilst in the intermediate rows the overlap is 
proximal, the free edge of the feather being turned towards the 
