1918.] Under Wing-Coverts of Birds. 557 



Median under coverts large, present on the cubitus, with 

 one besides at the carpal joint on the raanus ; overlap 

 contrary. 



In all the Doves examined the portion of the com- 

 plete or major row of reversed under coverts lying- on the 

 proximal part of the manus was found to have the contrary 

 overlap, as in so many other groups of birds. These under 

 coverts cliflFering in manner of overlapping from the others 

 on the hand, were noticed by Sundevall in Columba. But 

 he had laid down the rule that the feathers of " the second 

 series '^ (median under coverts) " lie with the margins in 

 the opposite direction to the former '^ (i. e. have the con- 

 trary overlap). This rule he considered so invariable that 

 " when either of the two series is deficient, we can recognize 

 by the position of the margins which it is that remains." 

 Following this rule with Columba, he says that in this bird 

 the first series (major coverts) is interrupted on the hand, 

 their place being taken by the second series (median 

 coverts). Against this view, that the feathers with con- 

 trary overlap are really median coverts filling a supposed 

 gap in the row of major coverts, it may be argued : — 

 (1) changes of overlap in the midst of either series of under 

 coverts are frequent, in many different birds, — the overlap 

 of each series is not uniform and invariable; (2) the feathers 

 in question, on the proximal part of the manus, cannot be 

 median covei'ts because there is one real median covert, — 

 the feather marked " a " in the figure of Tympanistria — 

 (two were found in Turturuma) in front of them, not 

 in the same row with them, (See remark under Ardea 

 goliath.) 



The characteristic in which the reversed under coverts of 

 Doves differ from those of the birds preceding them in this 

 paper (but not from those following them) is the reduction 

 in size of the major under coverts on the cubitus and the 

 counterbalancing increase in size of the cubital median 

 coverts, so that the latter become the principal under coverts 

 of that part of the wing. 



