THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



81 



center. A narrow gray circle or reflex ring 

 surrounds this pit. 



The optic disc has its central portion appar- 

 ently stippled with bright orange-red dots, 

 while its margin is fringed with coarse, white 

 fibres, that are also studded with brown pig- 

 ment dots especially near the outer border. 



The pecten is of the usual deep, chocolate- 

 brown color, rather narrow where it joins the 

 disc but becoming much thicker and more 

 massive as it projects into the vitreous towards 

 the lens. 



Brazilian Seriema. Cariama cristata. 

 This species presents an ophthalmoscopic 

 picture of the right eye, erect image, that is 

 reproduced as Plate XIX, page 139. The 

 dominant color of the fundus oculi is a dull- 

 drab. Over the lower quadrants of the 

 eyeground run rather straight, dull-red, cho- 

 roidal capillaries that fade away as they 

 reach the upper half of the field. This region 

 is also shot with a greenish-blue muslin-like 

 film, which is probably a reflection by the 

 retina of light rays from the ophthalmoscopic 

 mirror. Above the end of the disc is a small, 

 round depression, quite clear of any reflex. 

 To the inner or beak side of the eye is the 

 circular macula, whose diameter is about 

 three times that of the cavity at the end of the 

 disc. The center of the larger circle is quite 

 clear, with the exception of a bright shimmer, . 

 such as is sometimes seen about the human 

 fovea. The circumference of this circle is 

 very sharply defined, and has a bright ring 

 around it of glistening white. 



The optic disc appears as a long, white 

 oval, with irregular margins. 



The black-brown, corrugated pecten is very 

 large and long; it extends into the vitreous 

 and almost touches the lens with its club- 

 shaped terminal. Very fine opaque nerve 

 fibres radiate at regular intervals from the 

 whole papillary circumference. 



In two eyes of this bird examined by the 

 writer there were, in addition to the appear- 

 ances just detailed, several scattered, red- 

 dish-brown deposits, very slightly pigmented, 

 in the choroid. These were found in an 

 individual captive in the Bronx Park for four 

 or five years, and were probably pathological. 



Ardeiformes 



American Black-crowned Night Heron. 

 Nycticorax nycticorax nosvius. (Figs. 92 

 and 129; macroscopic view.) 



There were no definite, naked-eye indica- 

 tions of a fovea in the individuals examined. 



The pecten, more pointed at its superior 

 extremity, exhibits 20 convolutions, so sepa- 

 rated that a view of the disc borders is here 

 and there obtained. The pectinate coils are 

 united by a narrow, cord-like crest that ex- 

 tends on the same plane and in a straight line 

 (except that at its middle point it is slightly 

 higher) along the upper free border from one 

 extremity to the other. The coils do not 

 differ much in length. 



European Night Heron. Nycticorax 

 nycticorax. Seen with the ophthalmoscope 

 the eyeground (see Plate XX, page 139) is 

 dull gray, covered with grayish- white dots. 

 The lower part of the fundus exhibits a num- 

 ber of faint, reddish choroidal bloodvessels, 

 that run in a vertical direction, and whose 

 disposition is similar to the capillaries seen 

 in the fundus of the Boatbill, depicted in 

 Plate XXII, page 141. 



The optic disc is long, but of medium width, 

 with both extremities rounded. Its center 

 is orange-red and covered with minute, brown 

 pigment dots. 



The pecten is deep brown and its outlines 

 are well defined the whole length of the 

 papilla. Very thin grayish radiations extend 

 from the upper two-thirds of the optic 

 entrance. 



The macula is situated quite close to (and 

 towards the upper nasal aspect of) the disc. 

 It is surrounded by an outer ring of whitish 

 lines; then, towards its centre is a zone re- 

 sembling the surrounding, punctated retina. 

 In its exact centre is a small fovea composed 

 of gray -white striae. 



Great White Heron. Ardea occidentalis. 

 The individual examined by the writer had 

 been in captivity at the Bronx Park for sev- 

 eral years and was slightly myopic. The eye- 

 grounds of both eyes appeared identical and 

 the ocular organs were normal. The pupil 

 contracts under the strong light of the oph- 

 thalmoscopic mirror to medium size. 





