1882. DISCOLOURED SEA. 7 
rants, and immense herds of great unwieldy seals derive, on some 
parts of the coast, their chief sustenance from these swimming 
crabs. Seamen invariably attribute the discoloration of the 
water to spawn; but I found this to be the case only on one 
occasion. At the distance of several leagues from the Archipe~ 
lago of the Galapagos, the ship sailed through three strips of 
a dark yellowish, or mud-like water; these strips were some 
miles long, but only a few yards wide, and they were separated 
from the surrounding water by a sinuous yet distinct margin. 
The colour was caused by little gelatinous balls, about the fifth 
of an inch in diameter, in which numerous minute spherical 
ovules were embedded : they were of two distinct kinds, one being 
of a reddish colour and of a different shape from the other. I 
cannot form a conjecture as to what two kinds of animals these 
belonged. Captain Colnett remarks, that this appearance is 
very common among the Galapagos Islands, and that the divec- 
tion of the bands indicates that of the currents; in the described 
case, however, the line was caused by the wind. The only other 
appearance which I have to notice, is a thin oily coat on the 
water which displays iridescent colours. I saw a considerable 
tract of the ocean thus covered on the coast of Brazil; the sea- 
men attributed it to the putrefying carcass of some whale, which 
probably was floating at no great aistanee. Ido not here men- 
tion the minute gelatinous particles, hereafter to be referred to, 
which are frequently dispersed throughout the water, for ‘they 
are not sufficiently abundant to create any change of colour. 
There are two circumstances in the above accounts which 
appear remarkable: first, how do the various bodies which form 
the bands with defined edges keep together? In the case of the 
prawn-like crabs, their movements were as coinstantaneous as in 
a tegiment of soldiers; but this cannot happen from any thing 
like voluntary action with the ovules, or the conferve, nor is it 
probable among the infusoria. Secondly, what causes the length 
and narrowness of the bands? The appearance so much re- 
sembles that which may be seen in every torrent, where the stream 
uncoils into long streaks the froth collected in the eddies, that 
I must attribute the effect to a similar action either of the cur- 
rents of the air or sea. Under this supposition we must believe 
that the various organized bodies are produced in certain favour- 
