CAPTAIN TUCKEY’S NARRATIVE. 11 
the vicinity of soundings. Here I may observe, that should 
this discolouration of the sea at such a distance from the 
land be a constant circumstance, it may serve to guide 
ships which have no means of correcting their reckonings, 
and thereby prevent the shipwrecks that so often happen 
on the coast of the Desart in the vicinity of cape Blanco, 
by their not allowing for the easterly current that seems 
invariably to set quite from the English Channel to the 
Canaries, and the effect of which we found to be, in that 
distance, equal to one degree and a half of longitude. 
The towing-net was now become tolerably successful, 
taking up from time to time various species of mollusca, 
such as Portuguese men of war, (Holothuria physalis), 
Vellela mutica, (a Marc) Thalis trilineata, ( ib.) besides some 
testacea, viz. the Hela. zanthina, with the living animal ; 
many dead shells of the Nauéilus spiralis, &c. specimens of 
all which were preserved by Mr. Cranch. 
The holothuria made its first appearance on the 4th in- 
stant in latitude 24° 13’, longitude 18°31’, temperature of 
the atmosphere at noon being 68°, of the surface of the sea 
65°. These animals continued more or less abundant until 
past the Cape Verde islands, when they entirely disappear- 
ed. The greatest abundance of them was however on the 
