THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



109 



very minute, grayish-white dots. These dots 

 coalesce at the macula where they form a soft, 

 round area bordered by a light reflex. The 

 single macular region and fovea are situated 

 a little above the upper end of the pecten and 

 towards the nasal side of the optic nerve. 

 The pecten, very large and massive for the 

 size of the eye, is of the usual chocolate- 

 brown color; it is more or less club-shaped, 

 and extends well forward towards the lens. 

 At times it quite fills the area of the pupil, so 

 that the fundus is difficult to explore. The 

 pecten, whose outline is very irregular, covers 

 the papilla entirely so that it appears to 

 spring directly from the retina without show- 

 ing the white disc margin found practically in 

 all birds. From the sides of the apparent 

 root of the pecten a few, whitish, opaque 

 nerve fibres cross the field of view. 



Passeriformes. B. Tanagridce 



Scarlet Tanager. Piranga erythromelas. 

 The dominant coloration of the eyeground in 

 this species — readily seen by aid of the in- 

 direct method — is a clear, bright gray- 

 brown, sprinkled with numerous, glittering 

 whitish-yellow points. 



Law Bird of Paradise. Parotia lawii. 

 Plate LV, page 175, gives an ophthalmoscopic 

 picture of the fundus of the left eye, erect 

 image. 



The eyeground appears yellowish gray, or 

 khaki color, almost uniformly covered with a 

 dense mass of minute white dots, that are 

 smaller and denser at the macular region. A 

 few dull-red choroidal capillaries are visible 

 on the lower part of the fundus near the 

 periphery. 



The optic nerve head, dull-white, long and 

 narrow, has a rounded upper end. Its entire 

 central area appears as if it were a mass of 

 fine, brown pigment dots. 



The pecten is exceptionally long, rather 

 narrow, spirally arranged and extends beyond 

 the range of vision through the undilated 

 pupil. It is similar in many respects to the 

 fundus of the Common Pigeon. 



To the nasal side and a little above the end 

 of the disc is the macular region, which appears 

 as a dull-brown, crater-like depression bound- 



ed by a white mass of (reflex) striations. 

 Opaque nerve fibres radiate from both sides 

 of the disc but finally disappear as they 

 approach the boundaries of the fundus. 



Passeriformes. Corvidm 



Blue Jay. Cyanocitta cristata. The fun- 

 dus appearances as revealed by the ophthal- 

 moscope in the left eye of one of this species 

 is depicted as Plate LVI, page 175. The 

 general color of the eyeground is a slate-gray, 

 with an added pale-yellow tint in the lower 

 half of the eyeground. The entire field is 

 besprinkled with irregularly shaped, light- 

 gray dots, giving it the appearance of a rough 

 and rather coarse surface, especially near the 

 macular area where the dots are more closely 

 packed in the shape of a bright, circular 

 patch. 



The optic nerve-head is quite white and of 

 oblong shape. Several orange-colored, cho- 

 roidal capillaries are visible in this region, 

 covered with minute, brown, pigment dots, 

 like black pepper grains. Sprinkled about 

 each side of the optic disc is a large number of 

 opaque nerve fibres that extend across the 

 fundal field. 



The pecten, of the usual chocolate-brown 

 color, is rather irregular in shape at its supe- 

 rior extremity. From above downward it 

 looks like a tarred ship's cable, becoming 

 larger as it approaches its union with the 

 papilla. The length and thickness of this 

 organ (compared with the size of the eye and 

 pupil) make it difficult to follow its outlines 

 throughout. The superior end appears to 

 come well into the vitreous cavity and to 

 reach the lens. 



Steller Jay. Cyanocitta stelleri. (Figs. 

 Ill and 109; macroscopic view). The ocular 

 background of this species exhibits a moderate- 

 sized, though well-marked, single, circular 

 macular region. The foveola is shown as a dark 

 spot crowned by minute pigment grains that 

 mingle with a similar pigment ring of granules 

 that serve as a boundary for the whole region. 

 There is a small, kidney-shaped space be- 

 tween these two collections of dotted pig- 

 ment that seems free of color. The centre of 

 the fovea is slightly above and about half a 



