THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



83 



The dominant color of the background is 

 light-reddish or brownish-gray and has appar- 

 ently a granular surface. 



The papilla is white, almost entirely cov- 

 ered by the pecten and seems shorter than in 

 most birds. 



The pecten is unusually large; only its free 

 end, which is blunt and rounded, can be out- 

 lined with the mirror. There is no well- 

 defined macular region. 



American Egret. Herodias egretta. A 

 young adult was examined by the writer 

 in the Bronx Park. The dominant color of 

 the fundus in this species is a clear, bright, 

 steel-gray. 



The pecten, an oblong with rounded ends, 

 covers most of the optic disc, whose white 

 border can be seen only on the outer side. 

 Striae, composed of whitish opaque nerve 

 fibres, radiate from the circumference at 

 regular distances from each other. 



American Bittern. Botaurus lentigino- 

 sus. (Figs. 128 and 91.) This fundus when 

 seen by the naked eye and in prepared speci- 

 mens, shows two macular regions with their 

 fovea. The fovea nasalis — a large dot sur- 

 rounded by a nebular ring — just above and 

 slightly to the nasal side of the superior 

 extremity of the pecten. Temple-wards and 

 almost at the periphery of the visible back- 

 ground is the fovea temporalis — a less dis- 

 tinct area, also depicted as a central spot sur- 

 rounded by a ring of pigment grains. Allow- 

 ing for the concavity of the eyeball the two 

 maculae seem separated (in the figure) by 

 about two-thirds the length of the optic disc. 



The coralliform, fenestrated structure of 

 the pecten is made up of 28 narrow convolu- 

 tions that are separated at their upper free 

 margins so as to allow, here and there, a good 

 view of the pigment-dotted surface of the 

 opticus. There are three (unequally) short and 

 eleven (equally) long double coils joined 

 above by a narrow but uniform crest. 



European Bittern. Botaurus stellaris. 

 The left fundus oculi of this species is depicted 

 in Plate XXI, page 141 of this work. 



The eyeground, mostly mouse-colored 

 shading to yellow, is sprinkled with small, 

 dull-white dots. 



Almost immediately above the upper end 

 of the optic nerve entrance and towards the 

 nasal side of the disc is the macular area. The 

 fundal dots at this point are much duller in 

 tone and incline towards a dull, buff color. 

 The region of the macula, enclosed by two 

 circles, one within the other, is also char- 

 acterized by the presence of very short, 

 bright, bluish-green lines radiating from the 

 center of the fovea. These striations are very 

 brilliant and are easily seen by the aid of the 

 ophthalmoscope. 



The optic disc is ovoid, blunt at its upper 

 extremity, and appears as if its longer mar- 

 gins describe a series of small curves corre- 

 sponding to the folds of the pecten. The 

 disc on either side of the root of the pecten 

 is dull-brown; near by are small, orange-red 

 choroidal capillaries. The papillary margins 

 are quite white and, in contrast with the 

 shadow cast upon the neighboring field by the 

 dark pecten, the disc stands out in sharp con- 

 tour. Extending a short distance over the 

 fundi and about the optic disc are a few 

 opaque nerve fibres. The pecten, con- 

 voluted, with serrated margins, and of the 

 usual chocolate-brown color, extends below 

 the lower end of the optic disc, and is plainly 

 visible. It does not project far into the 

 cavity of the vitreous. 



Boat-billed Night Heron. Cancroma 

 cochlearia. The eyeground of this Central 

 American species is represented by Plate XXII, 

 page 141, and depicts the left eye by the erect 

 image. The prevailing coloration of the back- 

 ground is dull-red, covered with orange-red 

 dots. These punctate deposits are inter- 

 mixed on the upper half of the fundus with 

 smaller and brighter dots of a grayer tone. 

 On the lower half and on each side of the optic 

 nerve are a few orange-red choroidal capil- 

 lary vessels, that run in a vertical direction, 

 parallel to the long axis of the disc. 



The macula is situated towards the nasal 

 side of the nerve head. This sensitive area is 

 rather brighter in color than the surrounding 

 field, and several white dots are included in it. 

 These small dots, however, are noticeable 

 only when the light of the mirror is reflected 

 on the region in certain directions. Rather 



