476 SLONAKER. [Vol. XIII. 



Horse (Equus caballus). 



The band-like area is here very broad, 5-7 mm., and extends 

 horizontally across the retina. The nerve entrance is below 

 the center and slightly toward the temporal side. The blood- 

 vessels are very meagre, and, according to Muller, extend over 

 but a small portion of the retina, leaving the area centralis and 

 the entire upper part of the retina free from blood-vessels. The 

 blood-vessels are usually not visible unless they are injected 

 (PI. XXVII, Fig. 7). 



Cat (Felis catus domesticus). 



Chievitz (31, c) has described the area as round and not visi- 

 ble to the naked eye and located toward the temporal side of 

 the nerve entrance. Ganser (19) has described it as round, 

 and Krause (18) has stated that the cat possesses a fovea as 

 well as an area. The retinal blood-vessels (PL XXVII, Fig. 4) 

 would indicate as much as those of the sheep or cow the pres- 

 ence of a band-like area. Or the finer branches radiating 

 toward a common point on the temporal side of the nerve 

 entrance would suggest a round area similarly located as that 

 described by Chievitz. In most cases a region similar to that 

 indicated by the dotted lines and having the same macroscopical 

 appearance as an area is observed. This appearance may be 

 due to the tapetum lying behind. The lower margin of this area- 

 like region corresponds very closely with that of the tapetum. 

 In sections I have not found a well-defined round area, but a 

 general thickening over the greater part of the region indicated. 



Skunk (Mephitis mephitica). 

 Mink (Putorius vison). 



No area is visible to the naked eye, but in horizontal and 

 vertical sections an oblong or oval thickening is found located 

 a little above and on the temporal side of the nerve entrance, 

 which in these animals is central. 



Fox (Vulpes vulpes). 



A horizontal, band-like region extending across the retina 

 just above the nerve entrance may be seen with the naked eye 



