284 Roosevelt Wild Life .hiiials 



the shoals of their tributary streams. They begin migrating about the last of 

 April, according to Surface ('99, p. 240), when the temperature of the water 

 reaches about 45° F (I.e., p. 223). It is probable that there is a response not 

 only to the current but also to warming water, according to one of Gurley's laws 

 (Gurley, '02, p. 409). In general, the males tend to precede the females and 

 select the sites for their nests just above shoals or riffles on sand (Surface, '99, 

 p. 216). Migration takes place during the night, and they rest during the day, 

 attached to stones (I.e., p. 214). A male, or a pair, makes a nest by moving the 

 stones to the margin of an area about two feet in diameter (I.e., p. 214). 

 Deposition of the eggs is described by Surface as follows (I.e.. pp. 220-221): 

 "Many stones are left at the sides and especially at the upper margin of the nest, 

 and to these both lampreys often cling for a few minutes as though to rest. 

 While the female is thus quiet, the male seizes her with his mouth at the back of 

 her head, clinging as to a fish [host]. He presses his body as tightly as possible 

 against her side, and loops his tail over her near the vent and down against the 

 opposite side of her body so tightly that the sand, accidentally coming lietween 

 them, often wears the skin entirely off of either or both at the place of closest 

 contact. During the time of actual pairing, which lasts but a few seconds, both 

 members of the pair exhibit tremendous excitement, shaking their bodies in rapid 

 vibration, and stirring up such a cloud of sand with their tails that their eggs are 

 at once concealed and covered. As the eggs are adhesive and non-buo}-ant, the 

 sand that is stirred up adheres to them immediately, and covers most of them 

 before the school of minnows in waiting just below the nest can dart through 

 the water and regale themselves upon the eggs." As soon as the eggs are shaken 

 together the lampreys begin to move stones from one part of the nest to another, 

 and to bring more loose sand down over their eggs. They work at this from one 

 to five minutes, then mate again ; thus making the intervals between mating from 

 one to five minutes. The number of eggs in the average female is about 65,000 

 (Gage, '93, p. 460), or from 25,000 to 35,000 according to Surface ('99, p. 200). 

 From 20-40 are deposited at a time, and the whole period lasts from 2-4 days, 

 (p. 222). The duration of the spawning season, according to Reed and Wright 

 ('09, p. 391), extends over a period of about three weeks, from May 25 to June 15. 

 Surface ('99, p. 223) gives the period from 4-6 weeks. The eggs hatch in from 

 one to three weeks (I.e., p. 200). Gage ('93, p. 448) thought the larvae remained 

 in the nest about a month, until about half an inch long (12-15 mm). The 

 young undergo a complete metamorphosis. The larvae look much like worms 

 and live in burrows in the sandy, quiet margins of the streams. When they reach 

 a length of about five inches (120-160 mm) they transform (Gage, '93, p. 452). 

 The transformation from a burrow-living, blind, sedentary, worm-like animal to 

 the active, eyed, predatory kind requires probably a month or two (p. 454). These 

 transformations begin late in August and extend to the middle of October (p. 455). 

 Coventry ('22, p. 131) records observations made on Lake Lampreys near 

 Toronto, Canada, in a portion of the Humber River where it was about a hundred 

 feet wide and two feet deep, except occasional holes six feet deep, with the river 

 bed composed of clean gravel or shingle and slabs of solid rock. There were 

 frequent rapids. Nests of the lampreys were found in the more rapid waters of 



