The following is a description of the photographs which I have prepared in 

 studying this structure : — 



Plate VII., Fig. 1, is a portion of the underside of a Pink.footcd Goose 

 Primary, magnified six times. The lower two-thirds of the illustration shows the 

 tegmen covering the space between the barbs. The barbs in the upper oncthird 

 have open spaces between them with background of barbules. 



Plate VII., Fig. 2, is a portion of a Barb from a Goosander Primary, 

 magnified 5 5 times. This view shows the barb from the side, and it will be 

 seen that the tegmen entirely covers the barbules on the left. Towards the right 

 the tip of the tegmen has become detached from the barb, which is not usual. 



The tegmen appears in two forms, (1) a flat cover, (2) a curved cover. 

 There does not appear, however, to be any particular system about the construe- 

 tion, for while the Buzzard, Blackcock, Grey Partridge, Grouse, and Duck have a 

 flat tegmen, the Turkey, Pheasant, Capercaillie, Goosander, Gull, and Owl have 

 a curved tegmen. 



