THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



89 



Gannet. Sula. bassana. The picture of 

 the fundus, as shown in Plate XXIX, page 

 149, is the result of ophthalmoscopic exami- 

 nations of three healthy, adult specimens. It 

 depicts the left eye ; erect image. The general 

 color of the eyeground is dull-yellow with 

 a gray tint, everywhere covered with light 

 gray dots, that are most numerous on the 

 upper half of the fundus. Below and on 

 each side of the optic nerve are several 

 orange-red choroidal capillaries. These ves- 

 sels are fairly straight and run parallel with 

 the long axis of the disc. 



The nerve-entrance and pecten are situ- 

 ated rather high up in the field ; consequently 

 it is easy to examine the details of the peri- 

 papillary background. 



Above the upper end of the optic disc 

 and a little towards the nasal side, is a small 

 circular macular area, red in tone but sur- 

 rounded by a larger circle, like a gray shadow. 

 The margins of the latter gradually fade 

 into the background. 



The visible margins of the papilla, apparently 

 composed of coarse, white, opaque fibres, 

 are not, as in many species, covered by the 

 pecten. The central part, near the root of the 

 pecten, is orange-red in color. 



The pecten itself is evidently attached to 

 the disc for nearly its entire length, and 

 does not appear to come forward towards 

 the lens. 



Redback Pelican. Pelecanus rufescens. 

 The individual (male) examined by the 

 writer was five years old and had been 

 domesticated in the Bronx Park for at least 

 three years. His refraction, estimated by 

 the skiascope, was about +1.D. The general 

 coloration of the ocular background is a well- 

 diffused, light reddish-brown; in some parts 

 of the field verging on gray. The pecten is 

 very large — larger at its free than at its 

 papillary extremity — and twelve distinct 

 corrugations in it are visible and can be 

 counted by the aid of the ophthalmoscope. 



Although the canoe-shaped optic papilla 

 is almost entirely obscured by the mass of 

 the pecten yet it is uncovered towards its 

 temporal end, where it presents a very 

 white, pointed extremity; elsewhere it ap- 



pears reddish-brown. Radiating fibres sur- 

 round the disc, like a halo. 



Australian Pelican. Pelecanus con- 

 spicillatus. The fundus appearances of this 

 bird, as demonstrated by the ophthalmo- 

 scope, are portrayed in Plate XXX, page 149. 



The predominant color of the eyeground 

 is a dull but deep gray, sprinkled generally 

 with irregular dots, most numerous in the 

 upper part of the fundus. The lower quad- 

 rants of the field are covered with a dull, 

 orange-red, choroidal capillary system, dis- 

 posed in a vertical direction. The disc is 

 a wide, pointed oval, exhibiting a number of 

 bright-red orange ridges that are uniformly 

 stippled with black pigment dots. The 

 disc margins stand out as a clear white. 



The pecten, broad and massive, seems to 

 fill the pupillary area. It projects far into 

 the vitreous, reaching, indeed, the posterior 

 surface of the lens. In spite of its large 

 size and intraocular disposition both the free 

 and the attached ends of the organ can be 

 outlined by the ophthalmoscope. Passing in 

 a radial direction from its circumference is 

 a number of opaque nerve fibres. 



The single macular area is to be found on 

 the inner side of the fundus. It is surrounded 

 by a narrow, sharply defined, reflex ring of 

 greenish color. 



California Brown Pelican. Pelecanus 

 calif ornicns. A young adult was examined 

 on the Coronado Islands, Mexico, by the 

 writer. The pupils measured about 5 mm. 

 and were not affected by light, as the bird 

 had just died. The fundus was well seen. 

 There was a distinctly whitish background, 

 almost uniformly covered with minute gray- 

 black dots. The pecten was large, and of 

 the corkscrew type, almost covering the 

 whitish-yellow optic disc whose margins were 

 easily made out. This bird seems, from the 

 position of his eyes and their frontal disposi- 

 tion, to have binocular vision. 



Serpentariiformes 



Secretary Bird. Gypogeranus (vel Ser- 

 pentarius) serpentarius. The ocular back- 

 ground of this species presents a most unusual 

 appearance. The colored drawing (Plate 



