

PRESIDENT'S ADDRESS. Ixi. 



marine zoology of the British Seas, the illustration of the geo- 

 graphical distribution of marine animals, and the more accurate 

 determination of the Pliocene period (the geological epoch 

 immediately preceding the present time)." The late Professor E. 

 Forbes was the ruling spirit, and under the influence of his 

 enthusiasm great progress was made in the knowledge of the fauna 

 of the British seas. It was then supposed that the zero of animal 

 life was approached at the 100-f a thorn line. In 1839 the 

 Admiralty placed the " Porcupine " under the orders of a com- 

 mittee consisting of Dr. Carpenter, F.R.S., Dr. Gwyn Jeffreys, 

 F.R.S., and Professor Wyville Thompson, F.R.S., to work a series 

 of dredgings in the North Atlantic to the north and west of the 

 British Islands, which were carried on successfully to a depth of 

 2,435 fathoms (upwards of two miles and a-half) in the Bay of 

 Biscay. 



The fauna of the deep water of the western coasts of Great 

 Britain and Spain and Portugal showed a marked relation to the 

 faunas of the early Tertiary and the later Cretaceous periods. 

 These results revolutionised the ideas of E. Forbes, who had 

 divided the area occupied by marine animals into eight zones of 

 depth in which he supposed animal life gradually diminished with 

 increase of depth until a zero was reached at about 300 fathoms. 



In the winter of 1872 by far the most important expedition in 

 which systematic dredging had ever been made a special object left 

 Great Britain, when H.M.S. " Challenger," of 2,306 tons, was sent 

 to investigate the " physical and biological conditions of the great 

 ocean basins." About 70,000 nautical miles were traversed in 

 three years and a-half, successful dredgings were carried out fifty- 

 two times at depths exceeding 2,000 fathoms, and three times at 

 depths exceeding 3,000 fathoms. Animal life was found to exist at 

 all depths. Beyond the depth of 400 or 500 fathoms the faunas in 

 all parts of the world had much the same general character. Animal 

 life was found less abundant at the lower than at the more moderate 

 depths, but, as well-developed members of all the invertebrate 

 classes occur at all depths, this depended probably more upon causes 



