FISHERIES, GAME AND FORESTS. 195 



from New York city to Iowa. It takes its common name from the fact that it is 

 never found in any other body of water than a small stream. In fact, recent investi- 

 gations have shown that they have no cause to leave the stream that affords them 

 spawning beds and food for their young, as they transform into adults, pass directly 

 to their spawning beds, mate and spawn, and then die, without taking any food what- 

 ever in the adult stage. This feature is closely analogous to the general life histories 

 of some insects, which do all their feeding in the larval stage and have no functional 

 mouth part in the adult stage, but at the time of transformation are fuliy mature and 

 are ready to mate and lay their eggs without taking any further nourishment. Of 

 course, with such creatures, death ensues shortly after reproduction, and their 

 existence in the immature stage extends through a much greater period of time than 

 in the adult, the ephemeral existence of the adults enduring but long enough to 

 permit the individuals to reproduce their kind. This prolonged larval state, in com- 

 parison with the length of the adult, is true of both species of lampreys found here, 

 but is especially emphasized in the Brook Lampreys. For three years we have had 

 the larvae transform in our tanks and become fully adult within a short time. They 

 transform in the latter part of March and during the month of April, owing to the 

 temperature of the water over the sand and debris which they inhabit. The females 

 are at once completely filled with well-formed eggs and present the same appearance 

 as those that are commencing to form spawning beds in the streams. Their bodies 

 are considerably distended with eggs and appear quite distinctly reticulated, or as 

 though covered or rather lined with a fine network, because the white opaque eggs 

 show plainly through the semi-translucent body wall. 



In the adult Brook Lamprey the mouth is greatly contracted, the teeth are quite 

 rudimentary and, indeed, functionless, and the alimentary canal is permanently 

 atrophied, showing a generally degenerate form in comparison with the Lake Lamprey 

 as a type. The mouth is yet perfect as a suctorial organ, although toothless for all 

 practical purposes. It is used as' a suctorial organ in constructing and tearing down 

 its nests and in seizing and holding to the females while in copulo, and for holding the 

 adults in place so currents of water cannot wash them away. 



The very small teeth shown in illustration No. 5 are but points, or mere rudiments, 

 and would not be at all adapted to cutting through the scales and skin of a fish, and, 

 in fact, we have never known of a lamprey of this species having been collected upon a 

 fish; and of the hundreds of fishes which we have collected at various times of the year 

 in the stream where thousands of specimens of this lamprey abound and are found 

 at the spawning period, we have never seen one that bore a mark that could possibly 

 be construed as being the evidence of an attack of a Brook Lamprey, while the large 

 scars of the Lake Lamprey are often conspicuous on fishes caught up the stream, 



