342 
THE VOYAGE OF H.M.S. CHALLENGER. 
fully a foot in diameter, and had a thickness of several inches. The inferior surfaces were 
irregular and earthy, while the upper surfaces were mammillated and covered with little 
asperities, as is usually the case with the manganese nodules of the deep sea. The colour 
of the broken surfiices was black with reddish layers, and when polished they in places 
presented a massive appearance, with a dark lustrous aspect. The fragments were com- 
posed of successive, more or less concentric, layers, and were evidently torn away from 
very much larger masses or nodules by the action of the dredge ; a small portion of 
one of the fragments is figured in PI. III. fig. 1. 
Along with these manganese fragments were numerous branches of a Gorgonoid Coral 
{Pleurocorallium johnsoni). In some instances the axis of the Coral was attached to the 
manganese nodules ; at the ujjper right-hand side of PI. III. fig. 1 a portion of the base 
of this Coral is seen to be attached to the nodule. All the Coral was dead, and in some 
instances had a much decayed and corroded appearance, as shown in PI. III. fig. 2. The 
whole surface of the branches was coated by a thin rind of peroxide of manganese, 
sometimes about OT mm. in thickness, which cracked off easily on receiving a smart 
blow. The axis of the Coral was sometimes 2 cm. in diameter, was generally pure white, 
and took on a high polish ; it still retained a considerable quantity of organic matter, 
and contained 6 per cent, of carbonate of magnesia. In some instances the interior was 
dull white and largely impregnated with manganese following the minute structure of the 
branches, thus producing alternate zones of black and white. A portion of one of the 
smaller branches is represented in PL III. fig. 3, to which, at the lower part of the 
figure, a valve of Lepas is seen cemented to the branch of Coral by means of the man- 
ganese depositions. A large living siliceous Sponge [Poliopogon amadou) was attached 
to the branches of this dead Coral, along with other living animals. It is not impossible 
that the Coral may have lived at the depth from which it was dredged, but if the bottom 
has not sunk the other conditions of the locality appear to have changed since the time 
when the Coral lived, otherwise it is difficult to account for the fact that all the Coral 
obtained here, and at two neighbouring stations, was dead. From the large amount of 
organic matter in the axis of the Coral, it cannot be regarded as fossil, but the carbonate 
of magnesia indicates that it is, at least, very old. 
Station 16, 2435 fathoms. — Three or four manganese nodules, some of them nearly 
an inch in diameter, were obtained in the dredge. They are round, with a mammillated 
surface ; one of them had a palagonitic nucleus. Fragments of palagonite were also 
present in the deposit at this station, as well as at Station 12, 2025 fathoms. Along 
witli the nodules there were two or three sharks’ teeth and valves of Scalpellum thinly 
coatc<l with manganese. 
Stiitiou 61, 2850 fathoms. — In the trawl wore a piece of pumice, about 4 cm. in 
length, and several concretionary lumps of tufa, the largest about 7 cm. in length. 
The fragments of tufa are quite unlike the deposit, and have a slight coating of 
