THE TRUE FISHES. 189 



the bottom, lying upon its left side, the eye moving over, 

 the successive stages of the movement being shown in 

 Fig. 231, until both eyes are upon the right side, which 

 is now the upper portion. The mouth is generally twist- 

 ed to conform with the new position. On the lower 

 side the pigment-cells are not developed, and the skin is 

 white, but the upper surface is colored and susceptible 

 to change and adaptation to the prevailing color of the 

 bottom. 



NOTE. This protection, afforded many animals, is due to the con- 

 traction and expansion of the different colored pigment-cells that are 

 contained principally in the cutis. They contract or expand according 

 to the light reflected ; the impression is received by the eye and trans- 

 mitted by the sympathetic nerves. A blind flounder does not adapt 

 its color to the surroundings. By severing some of the nerves Pou- 

 chet produced, at pleasure, a fish striped on one side and spotted on 

 the other, etc. The experiment may easily be tried by placing floun- 

 ders on white, brown, and black bottoms, and changing them about ; 

 so also with the octopus, anolis, and many others. 



Order VI. Pediculati. Walking-Fishes (Anten- 

 nariidcc]. These are pelagic fishes, floating about upon 

 the surface of the sea among the vast fields of sargassum. 

 The body is compressed, and three or four inches long ; 

 the fins ornamented with barbels, so that they can be 

 scarcely distinguished from the weed, which they also 

 mimic in color. They are interesting nest-builders (Fig. 

 232), collecting the floating weed into balls as large as 

 a cheese, connecting it by bands of a glutinous secretion 

 probably taken from a special gland, as in the stickle- 

 backs (Fig. 206). The eggs are attached on the sides 

 and within. Allied are the anglers (Lophiida>) (Fig. 233), 

 so called from several spines on the head that have 

 upon their ends barbels of flesh. The spines move up 

 and down over the enormous mouth like a fishing-rod ; 

 the waving bait attracting the smaller fishes, that often 

 fall victims to the curious fisherman. Some of this fam- 



