THE FUNDUS APPEARANCES IN VARIOUS ORDERS OF BIRDS 



95 



small, dotted, pigmented deposits. The ocular 

 media were entirely clear. 



In the right fundus the pathological changes 

 were the same except that towards the nasal 

 side of the papilla there was a large, atrophic, 

 pigmented area extending almost to the 

 periphery of the fundus, entirely unlike the 

 smaller and narrower lesion in the left eye. 

 Altogether the morbid changes in the right 

 eye are more numerous than in the left. 



In a younger individual the coloration of 

 the background, the papilla, the pecten and 

 the macular region were precisely as in the 

 first-mentioned bird. The pathological le- 

 sions, however, were entirely different. They 

 appeared in each eye as four or five rather 

 small, round, pigmented exudates, having a 

 whitish atrophic (?) centre, much like the 

 medium-sized deposits in the human eye 

 when affected by a disseminated choroiditis. 



European Barn Owl. Strix flammea. 

 (Figs. 97 and 112; macroscopic view). This 

 fundus shows the single sensitive regions 

 {macula and fovea) on the temporal aspect of 

 the field, slightly above and less than the long 

 disc-diameter from the upper termination of 

 the optic entrance. The fovea is represented 

 by a large dot in the center of a number of 

 minute granules, surrounded by an untinted 

 area inclosed in a ring of still more numerous 

 pigment grains. 



The small pecten is made up of 14 short, 

 stout convolutions (the largest ten of equal 

 size) that only partially cover the nerve head, 

 which has pigment granules scattered over 

 its surface. The pectinate coils meet above 

 and are joined by a straight, thin, cord-like 

 crest. They all incline towards the posterior 

 free border. The upper free margin is about 

 half the length of the papilla. 



The fundus oculi of the British species, 

 painted from a recently captured specimen, 

 is depicted on Plate XXXVIII, page 157. 

 With Mr. Head, the writer examined many 

 of the Strigidae confined at the time (July, 

 1912), in the gardens of the (British) Zoolog- 

 ical Society. Those that had been caged two 

 years or more were plainly affected with 

 choroidal changes, mostly of the disseminated 

 choroiditic type, the choroidal atrophy and 



pigment deposits varying in amount but 

 nearly always more marked the longer the 

 birds had been imprisoned. 



The general tone of the eyeground in Strix- 

 flammea is dull gray with bright, clearly out- 

 lined, orange-red choroidal vessels distributed 

 all over the fundus, except at the macular 

 region. At this area the tint is much grayer, 

 being, in addition, stippled with small, irregu- 

 lar blotches of orange-red and gray dots. 



The macula is also suffused with a gray 

 reflex. It is situated above the upper end of 

 the optic disc and nearly in a line with the 

 long axis of that organ. 



The papilla is long and narrow, with pointed 

 ends, and is apparently made up of coarse, 

 white fibre-bundles the central portion of 

 which is covered with minute, brown, pig- 

 ment grains, that have a distinctly reticulated 

 appearance. These white fibres border the 

 nerve-head all around. 



The dark-brown, convoluted pecten of the 

 Barn Owl is much larger than that of the 

 Tawny Owl. It is also placed farther for- 

 ward towards the lens than the pecten of the 

 latter bird. Extending from both sides of 

 the disc are a few, dull-gray fibres that stretch 

 a short distance across the fundus and then 

 disappear. 



Two specimens of Strix pratincola and two 

 of Strix perlata revealed ophthalmoscopic 

 appearances quite similar to those seen in 

 Strix flammea, except that the fundi of the 

 two first-named species are generally of a 

 deeper gray. All these (four) individuals 

 were suffering from choroidal changes. 



Psittaciformes 



Great Sulphur-crested Cockatoo. 

 Cacatua galerita. (Figs. 98 and 133; mac- 

 roscopic views.) In this ocular background 

 there is no visible fovea or macular area. 



The medium-sized pecten exhibits rather 

 broad, rounded convolutions, some 24 in all, 

 that are joined above by a heavy process or 

 crest of irregular outline. The latter extends 

 one-half the length of the free upper border, 

 joining together nine equal-size double folds. 

 From this keel-like body the mass of the pec- 

 ten slopes off to the front, exposing portions 



