— 85 
ship, officers and men all in accord, and must cay I never 
spent a happier Sabbath on shore. 
“On Monday, drilling and the usual routine of duties em- 
ployed all on board, so I amused myself by throwing out my 
surface net from one of the purls. 1 had been curiously wacli- 
ing a singular red streak on the ocean stretching as far as the 
eye could reach, and was very desirous for a closer acquain- 
tance with it, as our course lay right through its midst. As 
we struck the outer edge of it, the streak was not so perceptible 
as when at a distance. Upon drawing in my net and placing 
its contents in a clear glass vessel, I found them partly animal 
and partly vegetable, the former rigid and sinking to the bot- 
tom the latter soft and floating. "With a good lens I was ena- 
bled to separate them, and the rigid masses appeared to be a 
species of minute Crustacea, probably feeding on the plant. 
This was a minute Alga, and from its peculiar undulatorv mo- 
tion, 1 presume it to be one or the murine Oscillatorise or near 
it. It is not improbable that it may prove similar to the one 
mentioned by Harvey as giving the red colour to the Arabian 
Gulf. He says ; 
“ This colour is due to the presence of a microscopic Alga 
“ ( Trichodesmium erylhrceum ) allied to Osoillatoria, and en- 
il dowed with similar motive powers which occasionally per- 
“ meates the surface-strata of the water iu such multitudes as 
“ to redden the sea for miles.” I carefully preserved specimens 
of both, in diluted alcohol to transmit to America for scien- 
tific examination. 
“On my voyage from America to Mauritius in the Monocacy 
U. S. Frigate, on the subsidence of a cyclone we met after 
leaving the Cape of Good Hoop, I saw the same phenomenon, 
but the patches of colour were olive brown, and the Alg® 
were not so minute as tlioso giving the red coulour to this 
part of the Indian Ocean. The whalemen say they often meet 
with the appearance immediatly after a heavy storm. To my 
surprise I fouud entangled iu the net, ono of the curious 
oceauic insects, belonging to the family of the Hydrometidce 
I believe. I have caught one about 25 miles from Port Louis 
and dozens iu the harbour. "What it feeds on I know not, but 
