122 PERCY SLADEN TRUST EXPEDITION. 
sulphuretted hydrogen. The only life obtained off it after a long haul were two Asteroid 
starfishes of milky-white appearance. 
With such a small number of hauls it is hard to be quite sure of the nature of the 
bottom; but certainly the slope off the reef seemed to be as determinate a talus-slope as 
we found off the reefs of the Chagos Archipelago. It is difficult, however, to understand 
the peculiarly hard but irregular bottom between the talus and the mud, @. e. at about 
300 fathoms; it may, perhaps, have been of purely local occurrence. There appeared to 
be no incrusting animals on the coral-masses which could consolidate them into rock. 
The most interesting perhaps of other sedentary forms was an animal represented by 
thin incrusting sheets of lime of brilliant white colour, often growing on loose coral- 
masses, forming rounded nodules of 2 inches or so in diameter. In general appearance 
they looked like the Lithothamnia which so commonly form similar nodules in 
shallow waters, but actually are specimens of a foraminiferan, Gypsina, the largest 
as yet recorded. We also secured specimens of red and other Polytrema. Sponges 
were very abundant, but generally came up much crushed.  Alcyonarians were 
represented by several Gorgonians, mostly small growths, but no living corals were 
obtained. The Stylasteride were represented by the branching Stylaster and 
Spinipora, a genus with short, blunt, finger-like branches which had not been obtained 
since the ‘Challenger’ Expedition. Free animal-life was very scarce and no plants 
were obtained. 
About 9 a.m. on the morning of Aug. 25 we found ourselves about halfway, almost in 
a direct line, between Mauritius and Cargados, and 1° 38' north of the former, finding 
bottom at 1962 fathoms. The bottom seemed to slope off gradually from Mauritius, and 
the depth was about what we expected to find from the previous soundings. The 
bottom-temperature was 35° F., and serial temperatures showed a gradual fall from 
74°4° at the surface to 73°5° at 75 fathoms, and 72°7° at 100 fathoms, a more rapid fall 
then commencing, 7. e., 66°5° at 150 fathoms, and 61°2°, 53:3", and 46°8° at 200, 300, 
and 400 fathoms respectively. ‘These temperatures closely agreed with those which we 
had got on the previous day and excited no comment. Indeed, we assumed that there 
could be no shallow water in the immediate vicinity, and, as we did not desire to 
approach Cargados too early on the following morning, we employed our time in taking 
a series of plankton hauls down to 400 fathoms. Unfortunately we neglected to 
examine the bottom sample, which was recorded by Captain Somerville as “ mud, 
elobigerina, radiolaria,” with the significant comment: “Large preponderance of fine 
washings. The heavy washings are chiefly casts of globigerina, thickly mingled with 
radiolarian shells. The consistency is muddy; the colour a light buff.” It is but 
justice to add that Captain Somerville evidently appreciated the character of the bottom, 
and probably would have further investigated its peculiar nature had we not been on 
board. As it was, we proceeded on our course to Cargados, leaving a bank of 34 fathoms 
within 80 miles of us, a shoal which Admiral Field informs us was discovered by a 
merchant steamer a few months later. We ought certainly from the bottom sample to 
have deduced the existence of such a bank, and we fear the fault lies with us rather than 
with the method. Bottom samples from upwards of 200 fathoms should certainly indicate 
a i ote 
