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Proceedings of the Royal Society 
same species. The dead branches were in many instances beginning 
to get coloured brown from deposited manganese. One of the 
earliest and most interesting of the “ Challenger’s ” dredgings was in 
1500 fathoms, about 200 miles south-west of Teneriffe. The 
dredge came up full of beautifully branching jet-black coral 
attached to a soft black rock. Thickly clustered among the 
branches were large siliceous sponges, like masses of spun glass. 
Both the rock and the enamel-like coating of the coral consisted of 
black oxide of manganese. The same has been found on the ridge 
connecting Teneriffe and Grand Canary at a depth of 1000 fathoms, 
and after severe storms it is sometimes washed ashore on the- 
islands. 
It is not unlikely that if the ground about the “ Challenger ” 
station in 1500 fathoms were closely and carefully explored a very 
interesting shoal might be discovered. 
The fragments of the crinoid obtained were determined by Dr 
Herbert Carpenter to be Adinometra pidchella , which is common in 
the Caribbean Sea. One specimen of it had been previously got by 
the “Porcupine,” in 477 fathoms, near Gibraltar. 
The temperature of the water was taken at different depths with 
the following results 
Depth (fathoms), Surf. 50 100 150 300 500 
Temperature (Fahr.), 68°*5 60°*2 56°*8 54° *8 51°*9 50°‘0 
After exploring this coral bank, so far as time permitted, the 
ship was directed towards Mogador, on the Morocco coast. Inde- 
pendently of the high land, which is visible for many miles at sea, 
the approach to the coast is indicated by a rapid fall in the tempera- 
ture of the water of the sea surface and a remarkable change in its 
colour. Outside the temperature of the surface was very constantly 
69° F. After sighting the land it fell at first slowly, then 
rapidly, and when two miles from Mogador it was only 61° F. 
The presence of this body of cold water must have an important 
effect in moderating the climate of places situated on this somewhat 
desert coast. In the open sea, and away from shore influences, the 
ocean water in all moderately warm latitudes has the same deep, 
transparent, ultramarine colour. In colder latitudes this becomes 
greenish-blue and green, and the water loses its transparency. The 
