HYBRIS. 71 



propose the name of Ili/bris. We shall dwell here, however, solely upon the pterylographic 

 differences. These are chiefly limited to the peculiar form of the outer branch of the inferior 

 tract, described above and clearly shown in Plate II, fig. 11 ; this agrees precisely with that of 

 CatJiartes, only differing in that in Hybris the contour-feathers are more numerous and stand 

 closer together. Here also I have had occasion to remark the formation of brood-spots by the disap- 

 pearance of the contour-feathers on that part of the main stem which lies opposite to the outer 

 branch. In the males which I examined at the same season of the year I did not find the brood- 

 spots. Twenty-four remiges, none of them with an emargination ; the first three nearly of equal 

 length, but the second really the longest. Oil-gland briefly cordate, very broad in front, with a 

 large, deeply penetrating cavity, and two minute feathers at the apex over the orifices, which 

 cannot be accidental, as I found them constantly. 



The facial disk, from which this genus receives its name, and which is most perfect in them, 

 consists in all the Owls of several rows of small, but strong and very much curved contour- 

 feathers, which originate anteriorly above the eyes at the base of the beak, are continued on the 

 sides of the forehead and vertex, descend in a curve behind the orifice of the ear, and continue 

 beneath this and the eye on the margin of the lower jaw until they meet again in a curve on 

 the throat in front, between the rami of the lower jaw. The whole region of the skin in which 

 these feathers stand is elevated in the form of a fold, especially at the spot behind the orifice of 

 the ear, and in this fold are inserted the very stiff tubes of the feathers described. Usually, 

 these small feathers are not seen at all, because the long, sparsely barbed, and partly setiform 

 feathers of the lores, the region of the eyes, and the chaps lie over them, and it is then 

 these that form the true disk, that is to say, the circle of feathers around the eye. In the region 

 between the eye and the ear these feathers are very numerous, and stand upon a second high 

 fold of skin which here rises suddenly from the integuments of the head ; this lies over the great 

 orifice of the ear and closes it (see Plate II, where in fig. 11 the fold is represented turned back). As 

 the disk increases in size, so does this fold, which may be appropriately named the ear-operculum ; it 

 is, therefore, exceptionally large in Str.Jlammea, but also tolerably strong in Sir. otus and brachyotus, 

 and in Str. aluco, uralcnsis, and lappoiiica. I found it to be small, indeed almost wanting, in 

 Str. nyctca, Str. nisoria, and the Little Owls. With this is connected the slight development of the 

 disk. The disk-feathers of Str. otus are particularly remarkable ; they consist of a large tube, 

 perfectly open above, upon which a very small, sparsely barbed shaft is seated. By this structure 

 they furnish a very definite proof in favour of the interpretation of the shaft, as a one-sided pro- 

 longation of the outermost, most divergent point of the upper edge of the tube. In proportion 

 as the disk becomes less perfect the fold of skin upon which the small, strong contour-feathers 

 are seated also becomes weaker, and those parts of the fold which are situated upon the face in 

 front of the eye are then probably always wanting. In such cases two separate small folds of skin 

 occur at the ear an anterior one forming the operculum, and a posterior one which may be 

 compared to the conch of the ear. 



