Occasional Papers of the Mnseuin of Zoology 7 



The same activity follows if the stream le\ el lowers rapidly, 

 so that their haunts are exposed. For instance, in 1913. when 

 the Hnron River level was lowered during the construction of 

 a dam, many larvae emerged to the surface of the mud flats 

 thus luicovered. 



When a larva is liberated in an aquarium or in the stream 

 it swims a short distance, then erects the body almost vertically, 

 head dow^nward, and burrows with a rapid vibratory move- 

 ment. It does not continue straight down, but turns horizon- 

 tally, then upward, forming a burrow in the shape of a flat- 

 tened U. The dorsal surface of the body is kept up])ermost 

 throughout this process. If the aquarium floor is covered with 

 but a thin layer of sand the l)urrow is much more flattened; 

 under these condition'? the tail frequently protrudes, but we 

 have never seen the head exposed. When disturbed, the ani- 

 mal leaves its burrow and swims vigorously. A\'hen placed in 

 an aquarium with no sand or other material the larva alter- 

 natel}- swims about and lies on its side — cither right or left. 

 As yet we have not determined the duration of larval life or 

 time of metamorphosis. It is to be noted that the habits, as 

 above described, are identical with those of the larvae of 

 lirifospliciiits 7^'iliJeri. 



Habits of .Jdiilts:"' The spawu.ing activities of 1905 were 

 first observed on ]\Iay 23, and they continued until May 2y ; 

 the last adtilt seen in that year was a weakened individual noted 

 June 2. For two or three days following May 2j the Mater 

 was so nitiddy that no observations were possible. Spawning 

 may have continued during that period. All the adults were 

 observed within a radius of twenty-five feet, on a bottom of 

 coarse gravel and shingle which contained stones from one to 



^ The writers are indebted to Prof. F E. Wood for the use of his notes on the 

 spawning habits of this lamprey. 



