52 NOTE ON THE YOUNG BLIND FISH. 



whole family of cods and their allies, to which group they belong, 

 essentially marine. Further than this the cat fish from the subter- 

 ranean stream in Pennsylvania belongs to a family having many 

 marine and brackish water representatives. As another very in- 

 teresting fact in favor of the theory that the Heteropygii were 

 formerly of brackish water, we have the important discovery by 

 Prof. Cope of the Lernsean parasite on a specimen of Amblyopsis 

 from the Wyandotte cave ; this genus of parasitic crustaceans be- 

 ing very common on marine and migratory fishes, and much less 

 abundant on fresh water species. 



Thus I think that we have as good reasons for the belief in 

 the immutability and early origin of the species of the family of 

 Heteropygii, as we have for their mutability and late development, 

 and, to one of my, perhaps, too deeply rooted ideas, a far more 

 satisfactory theory ; for, with our present knowledge, it is but the- 

 ory on either side. 



YOUNG OF THE BLIND FISH. Dr. Hagen gives me the follow- 

 ing information about the young specimens I mentioned (page 38) 

 as belonging to Dr. Steindachner, which I just missed seeing 

 before they were sent to Vienna. These specimens were procured 

 by Dr. Hartung for Dr. Steindachner under the following circum- 

 stances. Just as Dr. Hartung was leaving the cave hotel on Oct. 

 21, a bottle was brought to him containing four specimens, one of 

 which was smaller than the others (probably Typhlichthys) , all 

 living. He immediately transferred them to a jar containing alco- 

 hol and took no notice of them until he reached Nashville, when 

 he discovered an addition of eight little ones in the jar. 



The birth of these young was undoubtedly due to placing the 

 parent in the alcohol, and the date (Oct. 21) would correspond to 

 the time I have stated as probably that at which the young were 

 born. 



Dr. Hagen states that he examined the young under a lens, with- 

 out taking them from the jar, and could not discover any eyes. The 

 specimens were about three lines in length. 



So now we have two more facts to add to the history of the 

 blind fishes (though whether they apply to Amblyopsis or Typh- 

 lichthys is not yet settled). First, that the young are born in 

 October, and second, that they are without external eyes when 

 born. From the AMERICAN NATURALIST for February, 1872. 



