220 



Adaptations of Fishes 



constitute a continuous divergent series. The forms figured con- 

 stitute only a few of the stages of specialization and degradation 

 which the members of this group represent. 



FIG. 161. Sea-raven, Hemitripterus americanus (Gmelin). Halifax, Nova Scotia. 



Some of the features of the habits and development of certain 

 fresh-water fishes are mentioned in the following chapter. 



The degeneration of the eye of the blind fishes of the caves 



FIG. 162. Lumpfish, Cycloptems lumpus (Linnaeus). Eastport, Maine 



of the Mississippi Valley, Amblyopsis, Typhlichthys, and Trog- 

 lichthys, have been very fully studied by Dr. Carl H. Eigen- 

 mann. 



