2 3 2 ANIMAL LIFE 



known to the angler. The ephemeral may -flies hover 

 thick as snowflakes for the short afternoon that rounds 

 their winged life. The stone-fly flutters to a warm 

 resting-place, whisking its long tails. The alder-fly 

 rouses the fish to feast on the windfalls that every 

 puff provides. These gauzy hoverers are rising from 

 the water. The fringing weeds are hung with their dis- 

 carded suits. The river-bed has been crowded for the 

 past year with their creeping nymphs. (Frontispiece.) 

 The life-history of may-flies or ephemerida: lasts 

 from one to three years. The oval eggs are laid on the 

 surface of the water by the swarms of flies that hover 

 over a river for a day or two. They sink to the bottom 

 and become attached by anchoring threads to some 

 holdfast. After an interval these eggs give rise to 

 shrimp-like larva;, with two or three tail-filaments, 

 and just as there are many kinds of ephemera;, so the 

 larv;e are of different form and varying habits. All, 

 however, undergo many moults, acquire several pairs 

 of leaf-like gills, and pass by gentle gradations into the 

 winged state. Their adaptations to different modes 

 of life are of much interest. Some are burrowers, and 

 feed upon finely divided organic matter. These pos- 

 sess a long body, a small head, and dig with their 

 forelegs. The six pairs of feathery gills are kept 

 incessantly moving, and each contains a branched 

 air-tube as well as filamentous blood-vessels. The air 

 in these breathing-tubes is, however, not drawn into 

 them from the atmosphere, since there are no inhalant 

 openings from the surface, and it must therefore 



