220 



Adaptations of Fishes 



constitute a continuous divergent series. The forms figured con- 

 stitute only a few of the stages of speciahzation and degradation 

 which the members of this group represent. 



Fk!. 161. — Sea-raven, Uemitripterus 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, Cycloplervs hnnpus (Linnaeus). Eastport, Maine 



of the Mississippi Valley, Ainblyopsis, TypJiUchihys, and Trog- 

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

 mann. 



