is the oest possible proof of acute sight in fishes exactly 

 analogous to our own. 



That this faculty of vision includes a perception of 

 color as well as form is shown by the same facts ; but 

 there are other facts which seem to indicate it yet more 

 clearly. The teleosteans, which possess these developed 

 eyes and optic centres, are the only fish in which Mr. 

 Darwin has noted the occurrence of ornamental colors or 

 appendages, due, as he believes, to selective preferences 

 on the part of the animals themselves. It is curious, 

 too, that all the indirect proofs of color-sense in fishes 

 occur among this same group. The ornamental colors 

 generally coexist- with very excitable tempers, as is also 

 the case with such higher animals as the mandrill, the 

 peacock, and the humming-birds ; and in the little fight- 

 ing-fish kept as pets by the Siamese, the brilliant hues 

 are only displayed on the appearance of a rival or of the 

 fish's own reflection in a mirror. The moment the little 

 creature sees another of his own kind, he exhibits all his 

 coloring, and rushes against his enemy covered with 

 metallic tints, and waving his projected gills like the 

 wattles of a turkey-cock. Almost all the most beauti- 

 fully colored fish are coral feeders, dwelling among the 

 reefs and feeding off the bright polypes and other beauti- 

 ful creatures which abound in tropical seas. 



This case is again quite paralleled by that of birds and 

 insects ; for the most gayly colored species, like the but- 

 terflies, rose-beetles, humming-birds, parrots, loris, and 

 toucans, are flower-feeders or fruit-eaters ; and we may 

 well suppose that in every case a taste for color has been 

 aroused in the creatures themselves during their constant 

 intercourse with brilliant surroundings and their con- 

 tinual quest for brilliant kinds of food. There seems to 

 be, in fact, a regular gradation of color-sense and color- 



