500 The Cyclostomes, or Lampreys 



condition furnishes not only force to wash the sand over the 

 eggs when !aid, but also keeps the adult lampreys supplied 

 with an abundance of fresh water containing the dissolved 

 air needed for their very rapid respiration. Of course in such 

 rapid water the eggs are likely to be carried away down-stream, 

 but Nature provides against this by the fact that they are ad- 

 hesive, and the mating lampreys stir up the sand with their 

 tails, thus weighing down the freshly laid eggs and holding 

 them in the nest. Hence the necessity of an abundance of 

 sand at the spawning site." 



The Spawning Process with Lampreys. "There is much in- 

 terest in the study of the spawning process, as it is for the mainte- 

 nance of the race that the lampreys risk and end their lives; 

 and as they are by far the lowest form of vertebrates found 

 within the United States, a consideration of their actions and 

 apparent evidences of instinct becomes of unusual attraction. 

 Let us consider one of those numerous examples in which the 

 male migrates before the female. When he comes to that 

 portion of the stream where the conditions named above are 

 favorable, he commences to form a nest by moving and clearing 

 stones and making a basin with a sandy bottom about the 

 size of a common wash-bowl. Several nests may be started 

 and deserted before perfect conditions are found for the com- 

 pletion of one. The male may be joined by a female either 

 before or after the nest is completed. There is at once harmony 

 in the family; but if another male should attempt to intrude, 

 either before or after the coming of the female, he is likely 

 to be summarily dealt with and dismissed at once by the first 

 tenant. As soon as the female arrives she too commences 

 to move pebbles and stones with her mouth. 



" Sometimes the nest is made large enough to contain several 

 pairs, or often unequal numbers of males and females ; or they 

 may be constructed so closely together as to form one con- 

 tinuous ditch across the stream, just above the shallows. 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. He presses his body as tightly as possible 



