THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



91 



macula is another area, of a gray color, sur- 

 rounded by a fan-shaped, luminous reflex. 



The optic nerve-entrance is distinctly white, 

 and along its center is strewn a large number 

 of minute pigment dots. The outer margin 

 of the disc is bordered with black pigment, 

 as if a shadow were cast upon it by the pecten. 

 In this regard and in some others this fundus 

 resembles the eyeground of the Sea Eagle. 



White-bellied Sea Eagle. Haliaetus 

 leucogaster. The ocular fundi of three in- 

 dividuals of this species were found to be iden- 

 tical and furnish the ophthalmoscopic appear- 

 ances shown in Plate XXXIV, page 153. 



The coloration of the eyeground is mostly 

 dull-brown, the lower quadrants of the field 

 being covered with dull, orange-red capil- 

 laries evidently choroidal. 



The optic disc is a long white oval, whose 

 center is tinted with orange and covered with 

 tiny pigment dots. The papillary margins 

 are white bordered with black pigment. 



The upper half of the fundus is covered 

 by a mass of dull gray dots. There is a well 

 defined reflex near both maculae, each similar 

 in position to that seen in the Kestrel. These 

 areas are evidently very sensitive to light, as 

 the bird becomes very fidgety and irritable 

 when the reflected rays from the mirror are 

 thrown directly on one or other fovea. 



The pecten is very large and comes well 

 forward towards the posterior surface of the 

 lens. [Both extremities of the organ are 

 clearly visible through the ophthalmoscope. 

 There are very opaque nerve fibers to be seen 

 in any part of the eyeground. 



American Osprey, or Fish Hawk. Pan- 

 dion haliaetus carolinensis. When light is 

 thrown directly from the front and at a dis- 

 tance of one foot, on the pupils of this bird of 

 remarkable visual powers the red reflex is 

 seen to occupy fully three-fourths of each 

 pupillary area. 



By the aid of the ophthalmoscope the 

 writer found the general fundal coloration to be 

 bluish-gray with a suggestion of brown. 

 These tints are uniformly distributed through- 

 out the ocular background, and there is very 

 little of the striation seen in Buteo and other 

 genera. 



The pecten almost entirely obscures the 

 view through the pupil of the optic disc; it 

 is a compact, intensely black body, showing 

 about ten convolutions. 



Mainly because of the undilated pupil and 

 large pecten no definite fovea was visible. 



European Kestrel. Tinnunculus alau- 

 darius. Plate XXXV, page 155, is a faithful 

 reproduction of the ophthalmoscopic appear- 

 ances in this sharp-sighted species, depicting 

 the right eye by the direct method. 



The ground-color of the fundus is a light 

 brown, or brownish-gray. The lower quad- 

 rants are streaked with orange-red, choroidal 

 capillaries that run in a more or less vertical 

 direction, and become more distinct and 

 brighter red as they approach the periphery 

 of the field. The optic disc is a long, white 

 oval, showing its margins well beyond the 

 pigmented and fringed pecten. The central 

 area of the papilla appears to be hollowed out 

 like a canoe and the pecten does not overlap 

 it at any point of its circumference, as is so 

 frequently the case in avian fundi. 



The disc extends as far downwards towards 

 the fundal periphery as the observer's eye can 

 reach. At its lower extremity several small 

 choroidal vessels can be seen. 



The pecten has a rounded but pyramidal 

 form, sloping towards the centre of the disc 

 at both ends. It is of a dull-brown color, and 

 corrugated like a photographic camera. At 

 the junction of pecten and papilla are scat- 

 tered numerous brown dots, so disposed as 

 to give the former the appearance of a web. 

 The upper part of the eyeground is quite 

 devoid of choroidal blood-vessels, but is 

 covered with minute white dots. The fundus 

 is much clearer of the retinal shimmer or re- 

 flex noticed in most birds. 



The two macular regions are very distinctly 

 visible. The nasal macula is situated just 

 above the upper end of the disc and about 

 half a disc-length on the inner or beak side 

 of the eyeground. It is a dark-brown spot 

 with a pale area all around it. Outside of this 

 region and enclosing it are two distinct, pale- 

 green, filiform, reflex rings, the interior rings 

 being quite free from the white dots. On 

 the outer aspect of the eyeground, about 



