THE TROUT JUMP. 35 



beauty in fishes, the most highly perceptive being them- 

 selves apparently the most ornamented. There is also a 

 similar gradation of general sight-faculties : from the 

 case of a tropical shore-fish which can thrust its mov- 

 able eyes out of their sockets, and which hunts crusta- 

 ceans out of water on mud-flats at ebb tide, or of an open- 

 sea fish which swims half above the surface, and has its 

 eyes divided horizontally into two portions, one adapted 

 for vision in air and the other in water to the blind 

 fishes of the Mammoth Cave and of the marine abysses 

 revealed to us by the explorers in the Challenger. From 

 all these converging indications it is perhaps possible to 

 make a nearer guess at the visual faculties of fishes than 

 most people would be at first sight inclined to suspect. 



