FISHERIES, GAME AND FORESTS. 225 



degenerate third eye, shown in Illustration No. 7 ; also to the sense organ, in the 

 enlarged picture, No. 6. A comparison of the arrangement and development of the 

 teeth in the two species, as shown in Nos. 3 and 5, shows that the teeth of the Brook 

 Lamprey are rudimentary in comparison with those of the Lake Lamprey, but it does 

 not indicate that the latter has reached a further stage of development than the 

 former. The fact is that the Brook Lamprey has developed far beyond the present 

 stage of the Lake Lamprey, and instead of the teeth of the former being but 

 rudiments to indicate what is to appear, they are vestiges of what has been. Thus the 

 smaller species is an example of the anomalous condition of having degenerated from 

 a parasitic life and condition to a free and independent life, and has suffered atrophy 

 of organs in accordance. All evidences indicate that the Brook Lamprey has 

 descended from a true parasitic form similar to the Lake Lamprey at present, while 

 the latter has reached its present form through having been landlocked, and conse- 

 quently considerably modified in comparison with the present Marine Lamprey 

 {Petrotnyzon marinns L.). The modifications consist chiefly of a reduction in size 

 and an alteration (darkening) of color. Such changes are often seen in the true 

 fishes when they become landlocked from the marine forms, and learn to live perma- 

 nently in the fresh (sweet) waters. Such changes are seen in the ouninanche, or 

 landlocked salmon, and even in the alewife, or sawbelly (Pomolobus psetidoharengus), of 

 our own lake. Our Lake Lamprey, like these fishes, is a descendant of a true 

 anadromous marine form, and has learned to live throughout the entire year in inland 

 waters without returning to the sea; but, like them, in so doing, it has undergone 

 changes, in consequence of which systematic zoologists place it as but a variety of 

 the ancestral species. There is no doubt that the Lake Lamprey is the descendant 

 of the Marine Lamprey (Petromyzon marinus), which is abundantly found at present 

 on both sides of the Atlantic Ocean, and far up the streams that flow into it. It 

 occurs in numbers in the Susquehanna River, within twenty miles of the Cayuga Lake 

 basin. There is all evidence needed to establish the belief that the drainage from the 

 latter region was once southward through the river named, and this is doubtless the 

 route, rather than through Lake Ontario, by which the objectionable fish parasites 

 came into these waters. Even at the present time there is a plateau swamp near the 

 village of Dryden, in Tompkins county, which is so situated and connected that at 

 one end the water flows toward the northwest, into Cayuga Lake, and at the other end 

 it flows toward the southeast, into the Susquehanna River. In the stream between 

 this swamp and Cayuga Lake there is to be found a certain species of fish (Semotilus 

 corporalis), the fall fish or corporal, which is peculiar to the southeastern fauna. If 

 one fish or fish-like creature is able to come over the divide by this route, another 

 should be able to do likewise. 

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