THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



71 



right angles to the papillary margin are a 

 few opaque nerve fibres. 



A little above the superior end of the 

 optic nerve-head and towards the nasal 

 side, is a small, round, apparently somewhat 

 depressed macular area of a dull-gray tone. 

 From its margins runs a double row of fine, 

 blue-green, translucent lines which form 

 about it a broken or irregular reflex ring. 

 The bird becomes unusually restless when 

 the light from the ophthalmoscopic mirror 

 is focused on this part of the fundus. 



Glimpses of portions of the optic disc 

 show it to be dead white, and it seems to 

 have a fringe of short fibres of the same color 

 all about its edges. At the junction of 

 the pecten with the nerve-head, i.e., along 

 the central area of the latter, one sees numer- 

 ous brown pigment dots that appear like 

 small rootlets or capillaries and give a reticu- 

 late appearance to the papilla. 



The pecten itself has a dark chocolate- 

 brown color and a corkscrew contour; it is 

 unusually long and narrow, and its lower 

 segment appears to come well forward 

 towards the lens. 



Victoria Crowned Pigeon. Goura 

 victoria. The fundus oculi of this species, 

 depicted as Plate XI, page 131, right eye, 

 erect image, is of the usual gray color seen in 

 Pigeons and Doves. The eyeground gen- 

 erally is covered with minute white dots. 

 On the upper and nasal side of the fundus 

 is the macula, a small dull-gray area sur- 

 rounded by a gray and green reflex of small 

 lines. 



The optic disc is long, narrow, boat-shaped 

 and a little rounded at the upper end. It 

 looks as it were rather hollow and gray in 

 the centre, with a white rim all around. 

 A network of small, brown, pigment dots 

 is disposed along the centre on either side 

 of the pecten; and some opaque nerve fibres 

 extend across the fundus on all sides of 

 the nerve. 



The pecten is of the usual dark, chocolate 

 tint. It is corkscrew-like in appearance, 

 but one end is rather club-shaped and looks 

 as if it were covered with small brown nodules. 

 This segment comes well forward towards 



the lens, but not so much as in the Wood 

 Pigeon; otherwise the fundus closely re- 

 sembles the eyeground of that bird. 



Ralliformes 



American Coot. Fulica americana. 

 (Figs. 120 and 84.) The background of this 

 species, macroscopically considered, shows, 

 obliquely across the fundus but not reaching 

 the periphery at either end, a "split stick" 

 figure — a narrow band of unpigmented retina 

 depicted by two dotted lines of pigment, 

 the line towards the optic disc containing 

 more granules than the other. Midway 

 between the two ends of this figure is a 

 circle of pigment, twice the width of the band 

 itself, made by an extension of the pigmented 

 borders that form the boundaries of the 

 band. In the exact center of the circle is a 

 plainly marked pigment dot. 



The large, thick pecten is wider at its middle 

 than at either end. It has about 32 clearly 

 defined convolutions, or 16 double folds. 

 When seen from above one may perceive 

 between these plications not only the black 

 central body of the pecten but the papillary 

 edges. The free border of the pecten has no 

 definite keel but the upper margins of the 

 convolutions join to form a serrated wavy 

 line reaching from one terminal to the 

 other. This practically naked, saw-like 

 crest is unusual in the pectens the writer 

 has examined. 



The long axis of the papilla prolonged 

 to meet the retinal band makes with it an 

 angle of about 70°, the infulapapillary angle. 



Crested Coot. Fulica cristata. In the 

 several specimens examined ophthalmo- 

 scopically, the fundus appearances of this 

 Australian bird (see Plate XII, page 131) 

 were practically identical. The colored re- 

 production presents the left background by 

 the usual direct method. 



The predominant color of the eyeground 

 is dull gray, everywhere sprinkled with mi- 

 nute, white dots that are more clearly seen 

 above the superior termination of the optic 

 nerve and to the nasal side of the pecten. 

 Although this area is (judging from the 

 effect of the light thrown upon various 



