520 
THE VOYAGE OF H.M.S. CHALLENGER. 
could be detected either by the microscope, or by treating the red clay with weak 
acid. At 2325 fathoms there was 32 per cent, of carbonate of lime, consisting of 
the dead shells of pelagic Foraminifera and a few Rhabdoliths. At 2450 fathoms 
there was 1 or 2 per cent, of carbonate of lime, consisting of a few broken fragments 
of Foraminifera. At 2440 fathoms there was a red clay on the surface with only 
a small percentage of carbonate of lime, but three inches beneath the surface 
a much lighter coloured deposit containing a very large number of Foraminfera. It 
very frequently happened during the cruise that the deeper layers contained less car- 
bonate of lime than the surface ones, but only on two or three occasions were more 
calcareous shells noticed in the deeper layer of the deposit as in this case. The surface 
layer, it will be observed, was the same in nearly all respects as the deposit in 2450 
fathoms 80 miles to the eastward, and the deeper layer resembled that at 2325 fathoms 
still farther to the eastward, or the deposits in a lesser depth towards Raine Island, which 
contained over 50 per cent, of carbonate of lime. It is clearly illustrated in this section, 
that all the other conditions remaining the same or nearly so, the quantity of 
carbonate of lime found in a deposit is less the greater the depth. It has been stated 
above that this basin below 1300 fathoms is probably cut off from the colder water 
farther south, and, indeed, from general oceanic circulation below that depth. In all 
such basins the surface shells appear to be removed from the deposits at lesser depths 
than in areas where there is no interruption to free communication arising from the 
existence of submarine barriers. 
The mineral particles in these deposits consisted chiefly of angular fragments of 
volcanic rocks and minerals, all of small size except the pieces of pumice which were 
numerous in all the dredgings. There were many manganese particles, and, at the 
sounding in 1400 fathoms, some of the Foraminifera shells were filled with the peroxide 
of manganese, so that a complete internal cast of the shell was left after treatment with 
weak acid. 
Amongst Ccelenterata two specimens of Umbellulci leptocaulis, Kolb, and one of 
Batliyactis symmetrica, Moseley, and of fishes a new genus of Opliidiidse, Typlilonus 
nasus, Griinth., 1 and a new species of Stomiatidse, Echiostoma microclon, Gtinth., 2 were 
obtained with the trawl from 2440 fathoms, together with a few other animals. 
Tlie Opliidiid above mentioned had a large, rounded, fleshy head ; no trace of an eye 
could be seen other than a small dark spot a considerable distance underneath the skin. 
The fins were black, but the body of the fish was white ; with the exception of one or 
two, all the scales had been rubbed off, and with them apparently a thin, black skin, so 
that probably the fish when first caught by the trawl was of a uniform black colour ; 
the mouth and gill chambers were black. The total length was 10 inches, depth at vent 
2 inches. 
1 Ann. and Ma<j. Nat. Hist., ser. 5, vol. ii. p. 21, 1878. 2 Ibid., p. 180. 
