28 SCIENCE SKETCHES. 



this dark color often extends on the back part of 

 the body, so that the fish looks as if he had been 

 taken by the tail and dipped into a bottle of ink. 

 But with the end of the nuptial season, this color 

 disappears, and the fish regains his normal strawy 

 hue. 



The head in Boleosoma resembles that of Diple- 

 sion ; but the habit of leaning forward over a stone, 

 resting on the front fins, gives a physiognomy even 

 more frog-like. His actions are, however, rather 

 bird-like; for he will strike attitudes like a tufted 

 titmouse, and he flies rather than swims through 

 the water. He will, with much perseverance, push 

 his body between a plant and the side of the aqua- 

 rium, and balance himself on the slender stem. 

 Crouching cat-like before a snail-shell, he will snap 

 off the horns which the unlucky owner pushes tim- 

 idly out. But he is often less dainty, and seizing 

 the animal by the head, he dashes the shell against 

 the glass or a stone until he pulls the body out or 

 breaks the shell. Boly, alas ! is the " Quaker of 

 our aquarium " only in appearance. 



Gayest of all the darters, and indeed the gaudiest 

 of all fresh-water fishes, is the Rainbow Darter 

 (PoccilicJithys ccerideiis Storer). This is a little fish, 

 never more than three inches long, and usually 

 about two. Everywhere, throughout the northern 

 parts of the Mississippi Valley, it makes its home 

 in the ripples and shallows of the rivers and in the 

 shady retreats of all the little brooks. The male 

 fish is greenish above, with darker blotches, and 

 its sides are variegated with oblique bands alter- 

 nately of indigo-blue and deep orange, the orange 



