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.
Fig. 162.—Lumpfish, Cyclopterus lumpus (Linnæus). Eastport, Maine.
The degeneration of the eye of the blind fishes of the caves of the Mississippi Valley, Amblyopsis, Typhlichthys, and Troglichthys, have been very fully studied by Dr. Carl H. Eigenmann.
According to his observations
"The history of the eye of Amblyopsis spelæus may be divided into four periods: