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 Eemiges, and the Grreater 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 coverts 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. 



Pkoc. ZooL. See— 1886, No. XIII. 13 



