The Cyclostomes, or Lampreys 495 



find unsurmountable obstacles in their way, such as vertical 

 falls or dams, they turn around and go down-stream until they 

 find another, up which they go. This is proved every spring 

 by the number of adult lampreys which are seen temporarily 

 in Fall Creek and Cascadilla Creek. In each of these streams, 

 about a mile from its mouth, there is a vertical fall over 

 thirty feet in height which the lampreys cannot surmount, and 

 in fact they have never been seen attempting to do so. After 

 clinging with their mouths to the stones at the foot of the 

 falls for a few days, they work their way down-stream, care- 



FIG. 296. Kamchatka Lamprey, Lampetra camtschatica (Tilesius). Kamchatka. 



fully inspecting all the bottom for suitable spawning sites. 

 They do not spawn in these streams because there are too many 

 rocks and no sand, but finally enter the only stream (the Cayuga 

 Lake inlet) in which they find suitable and accessible spawn- 

 ing sites. 



"The three-toothed lampreys (Entosphem^s tridentatus] of 

 the West Coast climb low falls or rapids by a series of leaps, 

 holding with their mouths to rest, then jumping and striking 

 again and holding, thus leap by leap gaining the entire distance. 



" The lampreys here have never been known to show any 

 tendency or ability to climb, probably because there are.no 

 rapids or mere low falls in the streams up which they would 

 run. In fact, as the inlet is the only stream entering Cayuga 

 Lake in this region which presents suitable spawning condi- 

 tions and no obstructions, it can be seen at once that all the 

 lampreys must spawn in this stream and its tributaries. 



" In ' running ' they move almost entirely at night, and if 

 they do not reach a suitable spawning site by daylight, they 

 will cling to roots or stones during the day and complete their 

 journey the next night. This has been proven by the positive 



