Oceanic Phenomenon. 177 



distance of about one hundred yards from the entrance ; but 

 finding further progress all but impracticable, from the narrowness 

 of the passages, and the quantity of water of uncertain depth to 

 be encountered, we soon gave up the attempt, and were glad to 

 return to the cool and clear atmosphere of the upper air. 



During the voyage from Tonga to Fiji, we spent a good deal 

 of time in hunting up the reputed positions of certain doubtful 

 "banks," viz., the " Culebras" and "La Ranee" banks, with a 

 view to clearing up the question as to their having any real 

 existence except in the too vivid imaginations of the discoverers. 

 On the 24th of November, when in latitude 24 25' S., longitude 

 1 84 o' W., we steamed over the position assigned by the chart 

 to the " La Ranee" bank, and here our sounding line ran out to 

 three hundred fathoms without touching bottom, thus sufficiently 

 establishing the non-existence of any such " bank." Our position 

 at this time may be roughly stated as some two hundred miles to 

 the southward of Tongatabu. During the greater portion of the 

 day, the sea-surface exhibited large patches of discoloured water, 

 due to the presence of a fluffy substance of a dull brown colour, 

 which in consistency and general arrangement resembled the 

 vegetable scum commonly seen floating on the stagnant water of 

 ditches. This matter floated on the surface in irregularly-shaped 

 streaky patches, and also in finely-divided particles impregnated 

 the sea-water to a depth of several feet Samples were obtained 

 by " dipping" with a bucket as well as with the tow-net, and 

 when submitted to microscopic examination it proved to be 

 composed of multitudes of minute Confervoid afgce. On slightly 

 agitating the water in a glass jar, the fluffy masses broke up into 

 small particles, which, under a magnifying power of sixty diameters, 

 were seen to be composed of spindle-shaped bundles of filaments. 

 Under a power of five hundred diameters, these filaments were 

 further resolved into straight or slightly-curved rods, articulated 

 but not branching, and divided by transverse septa into cylindrical 

 cells, which contained irregularly-shaped masses of granular matter. 



12 



