90 



THE FUNDUS OCULI OF BIRDS 



XXXI, page 151), depicts the right fundus 

 by the erect image. The general color of the 

 eyeground is dull gray, pitted all over with 

 mixed light and dark brown pigment grains or 

 dots, the darker being about double the size of 

 the lighter granules. Interspersed with these 

 dots is a dense mass of minute, bright points 

 that cover the whole fundus, but they can be 

 observed only when the reflected light of the 

 mirror is focused upon them. These various 

 deposits give the background the appearance 

 of a rough surface. There are no visible 

 choroidal bloodvessels, but a thin layer of 

 translucent nerve fibers surrounds the papilla 

 for a short distance, particularly along the 

 long axis of the nerve-head. 



A little above the upper end of the optic 

 disc and towards the nasal side is the fovea 

 centralis, a round white dot enclosed by a 

 narrow ring of bright green. This area is 

 extremely sensitive to the reflected light of the 

 mirror. On the temporal side of the disc, 

 and above the end of it, is also a long, narrow, 

 sensitive area. This part is enclosed by a 

 shimmering reflex of green fight. The animal, 

 otherwise quiet, becomes very fidgety when 

 this area of the fundus is examined, and gasps 

 for breath as if it was being suffocated. 



The optic disc is long and rather narrow, 

 both ends being rounded off. It is quite white 

 and deeply pigmented at its outer and upper 

 borders. 



The pecten is of a lighter brown than usual, 

 is plainly serrated on either side and appears 

 as a narrow band that extends the whole length 

 of the disc. Just before its junction with the 

 optic nerve-head it is stippled with bright, 

 orange-red grains. The central part of the pec- 

 ten does not project far forward into the vitre- 

 ous; it appears to be quite narrow, while the 

 whole length of its upper edge or crest seems 

 rather wavy. On the whole, the fundus ap- 

 pearances present a picture unlike those of any 

 other species examined by Head or the writer. 



Accipitriformes 



Lammergeier. Bearded Vulture. Gypae- 

 tus barbatus. Plate XXXII, page 151, repre- 

 sents an ophthalmoscopic view of the right 

 ocular fundus (erect image) of this bird. 



The eyeground is slate gray, not stippled, as in 

 so many avian fundi, but presenting every- 

 where a granular appearance. The lower 

 half of the fundus is covered with dull, orange- 

 red choroidal bloodvessels that run in a ver- 

 tical direction, parallel to the sides of the optic 

 disc. 



Above the papilla (about two disc breadths 

 from it on the nasal side) is a small, round, 

 dark-brown pigmented pit, surrounded by 

 two distinctly marked, brilliant reflex rings, 

 each having a greenish tint. On the nasal 

 side of the nerve-head, but quite near the disc, 

 and much less distinctly outlined than the 

 depression just described, is the second macular 

 region with its fovea. Looking at it through 

 the mirror it seems to have a soft, indistinct 

 but dark center. 



All the fundal sectors are clearly seen. 



The optic entrance is pure white, with an 

 orange-red central area from which arises the 

 pecten. This body is very narrow and tapers 

 on its upper aspect for about one-fifth of its 

 length. It then becomes much broader and 

 almost covers the outer zone of the disk. As 

 it comes forward towards the lens its contour 

 resembles that of the Bald Eagle. 



This fundus is singularly free from opaque 

 nerve fibres. 



Bald Eagle. Haliaetus leucocephalus. 

 The fundus picture seen in Plate XXXIII, 

 page 153, is the result of an examination of a 

 number of individuals. The writer, for ex- 

 ample, had an ophthalmoscopic view of the 

 eyeground of five Bald Eagles in the Bronx 

 Park collection. 



The prevailing color of this bird's fundus is 

 dark reddish-brown, the lower half changing to 

 a dull orange-red. The whole eyeground 

 is covered with choroidal capillaries, and 

 dotted over with brown pigment grains, giving 

 it a rough, granular appearance. A gray 

 sheen pervades the upper part of the fundus. 



On the temporal side and some distance 

 from the upper end of the optic nerve is a 

 brilliant, white, round dot surrounded by a 

 small, light-green reflex ring, which is itself 

 enclosed in a very brilliant, narrow green 

 ring — the muscular region. On the nasal 

 side of the disc, and on a level with this 



