112 PR0CEEDING8 OF THE NATIONAL MUSEUM. vol. 4(5. 



former level. This fluctuation of the surface level is especially disas- 

 trous to lake species of dragonflies, as it entirely prevents the forma- 

 tion of a shore vegetation of aquatic plants, or beaches, such as 

 dragonflies usually frequent. 



The water of the lake is very cold, as the lake is fed entirely by the 

 torrents wliich rush down from the snow fields covering the surround- 

 ing heights. It is not clear for a mountain lake, but has a slight 

 turbidity of a dark swampy nature, possibly due to the recent flooding 

 of the burnt-over margins. 



Of the four species of dragonflies found about the lake, only two 

 occurred along the lake shore. Of these two, vEshna multicolor 

 patrolled the surface of the water, while Sympetrum corruptum caught 

 Diptera among the bushes or rested in the sunshine, perched on some 

 dead twig. Not more than 20 individuals of these two species were 

 seen, and neither species was observed pairing or ovipositing. The 

 other two species were found in a bordering swamp, several of which 

 occur here. All except one were cedar swamps, which were dark 

 and gloomy places, with the water completely shaded by the great 

 trunks and pendulous limbs of the cedar trees, and were seemingly 

 avoided by the light-loving dragonflies. 



The single open swamp was known at the lake as ''Cabin Swamp," 

 because on its bank stood a log cabin used by the forest rangers, by 

 whom the swamp itself had been fenced for a horse pasture. This 

 "Cabin Swamp" was on the south shore and about 2 miles above its 

 outlet. It was about 2 acres in extent, was covered with sedges and 

 swamp grasses, and contained but two or three shallow pools. 

 Toward the lake the swamp was bordered by a dense forest of black 

 pines, while over its opposite border towered the snow-capped ridge, 

 down the gullies of which roared the snow water which fed it. Nu- 

 merous clumps of various species of mountain willows, one species 

 only 12 inches high, dotted the grass, while everywhere over its 

 surface were bright yellow splotches of senecio, clumps of a low 

 purple flower, and many spikes of a white orchid. 



Three species of dragonflies were found in this swamp, Mshna 

 multicolor, AmpTiiagrion saucium, and SomatocTilora semicircularis. 



jEshna multicolor strayed in from the lake shore occasionally. 

 Two or three individuals were seen here, though none were taken. 



AmpTiiagrion saucium occurred here, though only three individuals 

 were seen^ — a single male and a pair in copulation, the female of 

 which was taken. This species hovered in the grass. 



SomatocTilora semicircularis was the species of dragonfly thoroughly 

 at home in this high cold swamp. The metallic luster of its green 

 body seemed in harmony with the icy water and cool bracing air, 

 spicy with the delicate perfume of the mountain orchids. As com- 

 pared with the other three species, Somatochloras were abundant, as 



