108 



THE FUNDUS OCULI OF BIRDS 



Fig. 142. American Crow (Corvus americanus) X8. 

 Macroscopic Appearances of the Fundus Oculi in the Preserved Eyes of Birds. 



in being uniformly light blue-gray. The 

 pecten obscured most of the field. 



British Siskin. Chrysomitris spinus. 

 One of this species, obtained from a dealer 

 and said to have been captive for six months, 

 was examined by the indirect method through 

 the small and undilated pupil. There was a 

 relatively large pecten which made it impos- 

 sible to outline the optic nerve-entrance clear- 

 ly or to determine the fundus details. How- 

 ever, the prevailing color of the eyeground 

 was light gray-blue, more or less regularly 

 besprinkled with minute, yellow-white dots. 



House Sparrow. Passer domesticus. 

 The ocular fundus of this typical species is 

 pictured as Plate LIII, page 173 the result 

 of the ophthalmoscopic examination of numer- 

 ous specimens. The dominant coloration of 

 the eyeground is pale-gray covered with very 

 fine white dots, closely packed together at the 

 macular area. They form a lighter zone a 

 little above the upper extremity of the pecten 



and towards the nasal side of the disc. From 

 the circumference of the optic disc a large 

 number of rather long, opaque nerve fibres 

 run in radial fashion towards the periphery 

 of the fundus. 



The papilla appears, when visible, to be 

 composed of irregularly shaped, brilliant, 

 white bundles; it can barely be outlined with 

 the mirror except at the upper (and narrow) 

 end of the pecten. 



The pecten has a deep red-brown color, and 

 its free extremity is long, narrow and of the 

 corkscrew type. The lower segment of the 

 organ extends well forward towards the lens 

 and, being large and massive, completely 

 covers the pupil and makes it impossible to 

 obtain a lateral view. 



Varied Bunting. Cyanospiza versicolor. 

 Plate LIV, page 173, represents the ophthal- 

 moscopic appearances of this species. The 

 prevailing color of the eyeground is dull gray 

 shading to buff. It is covered all over with 



