1044 FRESH-WATER BIOLOGY 



high, leaving the center of the nest concave like a saucer. The 

 nest is usually located near a log or large rock so as to be shielded 

 from one side. If the bank is sheer and the water deep enough, 

 the nest may be built directly against the bank." . . . 



After spawning the male drives the female away. "The male, 

 and the male only, now continues to guard the nest, fanning sedi- 

 ment from the eggs and repelling enemies. At 66 F. the eggs 

 hatch in five days and the young fishes swarm up from the bottom 

 in twelve to thirteen days from the day of hatching. 



" Shortly after the young small-mouthed bass rise from the nest 

 they scatter out over a space four or five rods across not in a 

 definite school with all the fish moving together, but as a loose 

 swarm, moving independently or in small groups. The fry may 

 be at the surface or on the bottom, in weeds or clear water, and are 

 attended by the male until they are ij inches long. The swarm 

 then gradually disperses and the young fry, which were previ- 

 ously black, take on the color of the old fish." 



Other fishes having adhesive eggs attach them to the lower 

 surfaces of rocks and boards. Several of our darters have this 

 habit, as well as several minnows. The eggs of some species of 

 darters are attached to the upper surfaces of rocks. Other fishes 

 suspend their eggs from aquatic plants, with or without nest 

 building. The goldfish, which has adhesive eggs, attaches them 

 singly to aquatic plants, as the fish swims about. The skipjack 

 probably does the same, though in this species, as in the case of 

 its marine relatives, the egg is supplied with long, thread-like fila- 

 ments. I have seen pairs of these fishes wind in and out near 

 the surface among water plants, and once saw a pair of gar pikes 

 late in June going through the same performance. The yellow 

 perch provides similarly for its eggs. They are laid in long strings 

 which are suspended from aquatic plants. The eggs of the stickle- 

 backs have mushroom-shaped processes that are adhesive. 



The lampreys, salmon, trout, some suckers, and some minnows 

 have eggs which are heavier than water. These fishes deposit 

 their eggs among the gravel of swift-flowing water where little 

 sediment falls. Some of our catfishes and the miller 's-thumb 

 have cohesive, agglutinating eggs. These are laid under boards 



