44 THE AUSTRALIAN NATURALIST. 
“‘A few summers ago I noticed a fine Cabbage Butterfly 
executing a number of gyrations in front of a milliner’s 
shop in New Bond Street, and making every effort to 
get through the plate-glass window. Immediately inside 
the window was a lady’s hat, ornamented by an enor- 
mous artificial scarlet poppy. It was quite clear that the 
object of the butterfly’s attention was the poppy. Ap- 
parently he was guided by sight, and not by smell.’’—Hd. 
Dracon-Fiy Larvan In Brackish Warer.—In con- 
nection with the power of aquatic larvee, normally living 
in fresh water, to adapt themselves to existence in water 
which is more or less saline, the following interesting note 
from Mr. Tillyard’s recently-published work, ‘‘The Bio- 
logy of Dragon-Flies,’’ may be profitably considered as. 
a sequel to Miss Froggatt’s paper on ‘‘The Saltwater 
Mosquito,’’ Aust. Nat., II., 1382, and that by T. Steel, 
IV., 12. 
On page 332 of his excellent book, Mr. Tillyard says :— 
“‘Dragon-flies are known to breed in coastal lagoons, 
where the water is brackish. Osburn, by a series of ex- 
periments, showed that the larvee could ‘withstand a salinity. 
up to a density of 1.01 (sea-water 1.026). At that point 
the larvae could live, but could not undergo metamor- 
phosis. At a density of 1.015 the larve suffered greatly, 
and soon died. The dragon-flies known to inhabit brackish 
water are (as might be expected) certain species of 
Inbellulinae, Anax, and some Agrioninae, to which we 
may add, in Australia, a few species of Austrolestes.’’ 
In the case of the Saltwater Mosquito, Culex vigilax, 
Steel found that as the water increased in salinity the. 
larvee remained for months without any appreciable in- 
crease in size, and died one by one, but were able to exist 
up to a Sp. Gr. of 1.165, equivalent to more than six 
times the salinity of sea water, or roughly, nearly 22 iste 
cent. of salt. ° 
The optimum density for dragon-fly larve found by 
Osborn, 1.01, is equivalent to about 14 per cent. of salt, 
or less than half that of sea-water, which contains 314 per 
cent. It is thus seen that the mosquito larve are infinitely 
more tolerant of saline conditions than are those of the- 
dragon-flies, —T nos. STEED. 
