No. 552] 



THE SEA LAMPREY 



731 



deeper and muddier; my observations were therefore 

 confined to the pebbly portion, a stretch of about half a 

 mile. Here a dozen nests were found, four with lam- 

 preys on them, the others deserted and partly scattered 

 by the tide. 



Nests. — The nest of the sea lamprey is similar to 

 that of other species, but much larger. It is a circu- 

 lar depression in the river bed, two to three feet in 

 diameter. One that was measured was two feet three 

 inches across, and six inches deep in the center. The 



nests are easily recognized, even at a distance of 

 several feet, by the large number of whitish quartz peb- 

 bles which have been uprooted and turned with their 

 clean faces up. They are built at random anywhere in 

 the river: near the bank, in the shade of overhanging 

 trees ; in the middle of the stream, exposed to the glare 

 of the sun ; or even, as with the nest shown in the figures 



