1886. ] CUBITAL COVERTS OF BIRDS. 185 
comparison of the features presented by a large series of living birds, 
in good health, or of freshly-killed wild birds, leads to a different 
conclusion. These show that a particular mode of arrangement, or 
a particular order of overlap, of the median cubital coverts is 
practically constant for all the individuals of the same species. More 
extended observations show that the same general mode of disposition 
is as a rule characteristic of all the species of a genus, and may even 
be found throughout all the members of groups larger than that. 
A reference to the wing of the Golden Plover, a central type, and 
one that in itself represents all the leading modifications (see 
fig. 1, p. 186), may help to make the nomenclature herein used 
more intelligible. [In drawing up this scheme I have availed myself 
of several suggestions made to me by Prof. Flower, and by my 
colleague Mr. E. T. Newton, after the paper was read before the 
Society.] The terms used refer mainly to the relations of various 
parts of the wing to each other and to the body axis, when the wing 
is extended and is viewed from the dorsal or upper surface. The 
wing-surface is primarily divided into the manual (primary) region 
and the cubital (secondary) region, this last embracing all the 
feathers that originate from any part of the forearm or cubitus. Of 
the manual region I have nothing that need now be discussed. In the 
cubital region the Remiges, and the Greater Coverts that come on 
next above them, are uniform in disposition in all Carinate birds. 
In these feathers the overlap is uniformly distal ; that is to say, the 
several feathers are disposed in such a manner that the outer free 
edges of those nearer the vertebral axis overlap the inner edges of 
those originating nearer the distal extremity of the wing. The same 
observation applies also (but with some minor modifications of detail 
that will not now be taken into consideration) to the Lesser Coverts, 
or those feathers that mainly originate in the Patagium, and that 
extend along the anterior border of the wing from the humeral fold 
to the carpal joint. The remaining feathers, which are generally 
comprehended under the term Median Coverts, vary considerably in 
both their direction of imbrication and in the number of rows that 
run parallel to the greater coverts in each case. The present paper 
is devoted to a consideration of the nature and the extent of the 
variation referred to, without regard to morphological details of any 
other kind soever. Many of the facts have either not been noticed, 
or else, if they have been noticed, their significance appears to have 
been missed. For convenience of description the tract occupied by 
the Median Coverts may be divided into three areas by lines parallel 
to the main direction of the cubital quills. The area nearest the 
vertebral axis will be referred to as the Proximal area, the next the 
Middle area, and the remaining third, up to the distal border next 
the manual region, the Distal area. The rows of feathers composing 
the median eoverts range, in a general way, parallel with the greater 
coverts. The number of rows varies from one to six, or even more, 
in different forms of birds; and the row nearest the greater coverts 
is the one most subject to variation in the disposition of the feathers 
composing it. 
Proc. Zooxu. Soc.—1886, No. XIII. 13 
