570 
THE VOYAGE OF H.M.S. CHALLENGER. 
Next comes Polysiphonia tuberosa (565 fathoms), whose handsome calycine form is shown 
in fig. 189b, while fig. 189a represents the animal as seen from above. The tentacles 
have here become short wide-mouthed tubes, whose bases are swollen into curiously 
shaped pads (fig. 190). In Sicyonis crassci (1600 fathoms) the tentacles are only small 
warty or sucker-like rings ; in Polystomidium patens (1825 fathoms) and Polyopis striata 
(2160 fathoms) their walls are almost entirely lost, so 
that the terminal opening has become a slit in the oral 
disk, an annular ridge, which surrounds the aperture, 
being the sole remnant of the tentacle-wall. Finally, 
in the genus Liponema (1875 fathoms), only simple 
openings indicate the places where the tentacles 
should stand. 
“ Thus then, of the twenty species hitherto 
described from depths of 500 to 2600 fathoms, not 
less than six species have shown modifications of the tentacles in one direction, whilst no 
such change has been observed in any one of the very numerous forms which belong to 
the coast-fauna. This makes it probable that the retrograde metamorphosis of the 
tentacles is a consequence of living in the deep sea ; and, indeed, peculiarities in the 
conditions of existence which there obtain can be suggested which might be 
favourable to a metamorphosis of the tentacles into tubes. Probably the nutriment 
of the deep-sea animals consists of matters which are far advanced in decomposition 
and of soft consistence. Such substances, suspended in water or embedded in mud, 
could not be seized by tentacles, but might be readily .absorbed by suctorial apertures or 
tubes.” 
Amboina. 
On the 4th October, at daylight, the green hills of Amboina were in sight 1 8 miles 
off, but the summits were hidden in the clouds ; it was found that a current of 1 2 miles 
to the westward had been experienced during the night. At 7 a.m. the ship was swung 
to ascertain the errors of the dipping needle, but the day was far from favourable for this 
purpose, the weather being overcast with frequent rain squalls, so that it was impossible 
to complete the observations, and at 3 p.m. the ship rounded Noessaniva Point, and 
proceeded up the harbour. 
On the peninsula of Leytimur, the southeast peninsula of Amboina, three distinct 
hills are seen from seaward, the easternmost being the highest (2030 feet by the chart) ; 
about 5 miles to the westward of this peak is a second hill, longbacked and slightly 
lower ; the land then falls to the westward in a series of rugged slopes, rising again at a 
distance of 2 or 3 miles from Noessaniva Point, to a round grass-covered hill, which 
