930 
THE VOYAGE OF H.M.S. CHALLENGER. 
the Equator; from thence northwards, light variable winds were experienced to the 10th 
parallel, but north of that parallel a fresh N.N.W. breeze was experienced, which obliged 
the vessel to stand off on the starboard tack. As the distance from the shore increased, 
the direction of the wind altered to the northward and N.N.E., which enabled the ship 
to fetch Porto Pray a on the 16 th April. On the 10th a very fine water-spout was 
observed some miles from the ship. 
On this trip three dredgings, four soundings, and eight serial temperatures were ob- 
tained. The depths ranged from 2010 fathoms to 2450 fathoms, and the deposit in each 
case was a Globigerina ooze, containing 94 per cent, of carbonate of lime in the former and 
65 per cent, in the latter depth. Only one or two small fragments of Pteropod shells were 
observed in fliese deposits, in which the carbonate of lime consisted chiefly of the shells of 
pelagic Foraminifera, Coccoliths, and Rhabdoliths. The remains of siliceous organisms did 
not make up more than 1 per cent, of the whole deposit. The mineral particles were exceed- 
ingly minute, and consisted of fragments of felspars, hornblende, augite, and magnetite. 
During a few days when the weather was calm there was an extraordinary abundance 
of life on the surface. Oscillatorise covered the sea for miles, and vast numbers of 
Radiolaria, belonging to the genus Collozoum, which contains all the skeletonless 
Eadiolarian colonies, were taken in the nets. The Foraminifera, belonging to the genera 
Pulvinulina, Pullenia, Sphceroidina, and Globigerina, were very large and very numerous 
on the surface, and their dead shells made up the principal part of the deposit at the bottom. 
Pelagic Diatoms . — Conte Abate Francesco Castracane, who is engaged in the pre- 
paration of a Report on the pelagic Diatoms collected by the Expedition, writes : — 
“ Although the study of the pelagic Diatoms collected by the surface net during 
the voyage of the Challenger has not led me to any noteworthy general deductions, 
nevertheless I have made a large number of observations which will greatly increase- 
our knowledge of the biology and morphology of these interesting forms. 
“ I tried to ascertain whether there existed any laws governing the geographical 
distribution of Diatoms, but the result was almost nil. I found not a few forms 
common to gatherings made in portions of the sea separated by enormous distances 
from each other, and these I regard as cosmopolitan ; nor is this to be wondered at when 
it is remembered that the different oceans communicate with each other, and that the 
action of currents constantly tends to mix the various floras. 
“ The Antarctic flora has, however, yielded forms of Diatoms, for which new genera 
must be constituted, such as Dactyliosolen, related to Phizosolenia, and Coretron, a new 
type of Chcetoceros, which have not been found hitherto either in the Arctic waters or in 
any other seas. But do we know the Arctic and Antarctic floras with sufficient accuracy 
to be able to speak with authority upon their differences ? 
“ The study of the surface collections has established the distinction between the 
