422 Simon Henry Gage 



From these, the present connections, and from the possible 

 connections with the Susquehanna and Hudson rivers at an 

 earlier date, it is to be expected that the aquatic fauna of 

 Cayuga and the other inland lakes would be rich and varied. 



By assiduous personal study and observation and the wise 

 direction of students, Professor Wilder has shown that in the 

 Cayuga lyake basin there are 21 families, including 40 genera 

 and 59 species representing the group of fishes. 



A further study of the outlets of these lakes, to Lake On- 

 tario and thence to the ocean, reveals the fact that they are 

 long and tortuous, and besides possess many rapids and 

 shallows. These conditions have probably obtained in recent 

 geological time, a time sufEciently great to lead one to expect 

 that the lake forms, especially those that had ceased to be 

 migratory, would have received a certain stamp or impress 

 from the special and somewhat isolated environment. Further- 

 more, migratory or anadromous forms, in bodies of water like 

 these, where they are surrounded by plentiful food, might grad- 

 ually become less migratory and as the difficulties of reaching the 

 ocean were increased by changes in the character of the out- 

 let or the gradual recession of the ocean, they might finall}' 

 remain permanently in the fresh inland waters, and like the 

 other permanent inhabitants be modified by the special en- 

 vironment. 



The more this lake fauna is studied the clearer does the 

 local coloring, so to speak, appear. Among the lampreys, 

 the subject of this paper, there appears not only the local im- 

 press but almost positive evidence that forms, at one time 

 naturally passing their adult life in the ocean, have become 

 accustomed to remain permanently in fresh water with corres- 

 ponding changes in the more impressionable or less important 

 parts. I say more impressionable, for it is one of the fruits of 

 modern research, in the light of evolution, that the most 

 fundamental organic structures, having to do with the mere 

 existence of an organism without regard to its upward pro- 

 gress, are more persistent and less changeable than less 

 ancient and less important organs, that is, less important from 

 the mere existence standpoint. 



