732 THE AMERICAN NATURALIST [Vol. XLVI 



(Figs. 1 and 4), partly under a log. Occasionally two 

 nests adjoin so that their peripheries overlap. 



Standing in the water close to a nest, one may observe 

 minutely every movement the lampreys make. One may 

 even stroke them or lift them by the tail without disturb- 

 ing them. A "fish" must be raised to a considerable 

 angle before it will loosen its hold on the stone to which 

 it clings, and dart away; and then it will go only a short 

 distance, fifty or a hundred feet, and seek refuge under 

 the "river grass." 



The manner of building the nest is quite like that of the 

 brook lamprey (Lampetra ivilderi), as de- 

 scribed by Gage ('93), and by Dean and 

 Sumner ('97). But owing to the large 

 size of the species all the processes are 

 writ large, as it were, so that one can see 

 the purpose of every movement. Build- 

 ing the nest consists in carrying the 

 pebbles and stones out of a circular area 

 until a basin-like depression is formed. 

 As the work proceeds the finer material 

 in the interstices between the pebbles 

 gradually accumulates, so that the bottom 

 of the nest becomes covered with sand and 

 fine gravel. The stones are seized with 

 the circular mouth to which they cling en- 

 tirely by suction. The "teeth" play no 

 fig. 3. Freshly part in this work, as may be proved by ex- 

 taJ d to a Tstone Perimenting with the freshly dead ' ' fish. ' ' 

 d b uced!rih°bu«S By P ressin g tne mouth of such a "fish" 

 funnel when the against a stone, it may be made to hold on 

 agTinst it. PTeaaed so tenaciously, that by lifting the stone 

 one lifts the fish (Fig. 3). A vacuum is 

 produced inside the buccal funnel, and this is the imme- 

 diate cause of the hold. In carrying stones out of the 

 nest, the procedure varies with the size of the stone. 

 Small stones, an inch or two across, are picked up in the 



