322 MR. W. P. PYCRAFT ON THE BIRD’S WING 
The fifth pair of coverts, however, embrace no remex. Whenever 
we find the wing-coverts disturbed in the manner indicated, we always 
find it accompanied by the absence of a remex from between the 
fifth pair of major coverts. 
But the absence of the quill between these coverts is not always 
associated with a disturbance such as that indicated above, as 
witness the Parrots. Fig. 5 shows the nature of the arrangement 
in the diastataxic wing. 
No explanation of this was forthcoming till recently, when the 
writer and Dr. P. Chalmers Mitchell were enabled to throw con- 
siderable light upon the subject. 
Dr. Mitchell distinguishes those wings which lack a remex 
between the fifth pair of coverts as diastataxial, and those in 
which the wing is complete in this respect as eutaxial. 
It was shown, by the writer, that, in the embryo, all wings are, 
at first, eutaxial ; later some become diastataxial. 
The eutaxial wing can best be studied in the 5 — 8 day chick. 
The feather papillae in these stages can be seen with ease. 
They will be found to be arranged in quincunx, so that perfect 
feather rows can be traced in both horizontal and oblique 
directions. 
The first feathers to appear are the remiges and the major 
coverts. In the early embryonic stages of the Plover, for instance, 
only these two rows are represented, and the wing is, furthermore, 
eutaxial. Simultaneously with the appearance of the rows in 
front of the major coverts, a process of shifting takes place. 
The nature and extent of this shifting is shown in Fig. 5 A, which 
represents a later stage of development than that described above. 
It will be seen that remiges 1 — 4 have moved slightly outwards, 
towards the tip of the wing, and, at the same time, backwards and 
downwards towards the under surface. Coverts 1 — 5 of the 
major, median, and minor coverts have moved likewise in the 
same directions. As a result, we have the “faulting” already 
described. This faulting accounts for (1) the presence of an 
“ intercalary row ” and (2) the mystery of the absence of a quill 
from between the fifth pair of major coverts. 
The intercalary row is seen to be nothing more than the first five 
feathers of the first row of minor coverts, which by the backward 
