THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



79 



The pecten, of the usual chocolate-brown 

 color, is divided into (about) fourteen con- 

 volutions, which are more massive below. 

 They extend well forward towards the lens. 



At the apparent junction of the pecten with 

 the optic nerve the disc is rather orange-red 

 in tone. 



Great Black-backed Gull. Lams mari- 

 nus. Plate XVI, page 135, depicts the fundus 

 appearances of the left eye in this species. 

 The general coloration of the eyeground 

 varies from a dull gray to a dull brown — 

 mostly the latter — traversing which are 

 many reddish, choroidal bloodvessels running 

 more or less in a vertical direction. It is the 

 number and visibility of these capillaries that 

 give the red tone to an eyeground essentially 

 gray. 



The optic disc is a long, narrow oval, quite 

 white, with a quantity of fine gray lines radi- 

 ating in all directions from the papillary mar- 

 gin. On the inner aspect of the eyeground 

 the macula is seen. It is situated about one 

 disc-length from the upper end of the pecten 

 and half a disc-length above the end of the 

 same organ on the inner side. 



The macula resembles a blue-green flake of 

 iridescent glass. It is of oval shape with a 

 reddish-brown center, which, however, is 

 unprovided with a reflex ring. 



The pecten appears to be in folds; the lower, 



or broader, portion extends well forward 



towards the lens and turns towards the nasal 



side of the bird's head. The inner quadrants 



of the fundus are more easily seen with the 



ophthalmoscope than the outer half but, so 



far as the latter area is visible, there is no sign 



of a second macula on the outer part of the 



eyeground. 



Charadriiformes 



Black-bellied Plover. Squatarola squa- 

 tarola. (Figs. 126 and 89; macroscopic 

 view.) Preserved eyes of this species present 

 a moderately broad, grayish retinal band, 

 whose borders, drawn as pigmented through- 

 out, extend somewhat obliquely across the 

 fundus from one margin to the other. Near 

 the middle point of this retinal area is a cir- 

 cular, crateriform disc so set in the ribbon- 

 like figure that its circumference is not pig- 



mented within the band proper but is con- 

 tinuous with the tinted borders themselves. 

 In some individuals there are traces of a 

 groove in the retinal band. 



The pecten in shape resembles that of the 

 Hudsonian Curlew. It has 24 sausage-like 

 convolutions; its fringed keel being prolonged 

 at the inferior extremity into a spinous process 

 that (not shown in the cuts) follows the con- 

 cavity of the eyeball and almost reaches the 

 margin of the lens. One-third of the coils 

 present a concave surface to the posterior free 

 margin. 



The infulapapillary angle is about 50°. 



In prepared specimens the eyeball is ovoid, 

 with axes 8:9. In some individuals, also, 

 there are traces of a groove in the retinal band. 



Hudsonian Curlew. Numenius hudsoni- 

 cus. (Figs. 125 and 88; macroscopic view.) 

 The background of this bird's eye shows a 

 broad, grayish band, with evenly dotted bor- 

 ders, that extends almost horizontally across 

 three-fourths of the visible fundus. It is 

 equally divided throughout its whole length 

 into two parts by a plainly marked line. 



The major axis of the papilla projected 

 towards the band describes with the latter an 

 angle of 50°. It bisects it half the axial length 

 from the crater-like fovea. 



The pecten, carrot-shaped from above, has 

 a fringed cap covering its upper free border. 

 It exhibits 34 convolutions, the spaces be- 

 tween the middle ten being deep enough to 

 allow a glimpse of the optic margins, that 

 are elsewhere completely covered. The 

 black, free margin corresponds in shape to the 

 pectinate body, being quite broad below, 

 narrow and pointed above. Its inferior third 

 is prolonged (into the vitreous) in the shape of 

 two conical elevations and a long, single 

 notched spine. The crest gradually slopes 

 from behind forward so that the posterior- 

 coils are the longest. Two-thirds of the coils 

 "face" forward. 



Greater Yellow-legs. Totanus melano- 

 leucus. (Figs. 114 and 87; macroscopic 

 view.) In this species a broad retinal band, 

 faintly depicted with pigment fines, extends 

 across the entire visible field, its nasal half 

 being divided by a double-dotted line that 



