The time may come when there will be no portion of the earth’s surface that has not been surveyed and explored by man. The work of enterprising travellers has now been carried on within a measurable distance of the North Pole; the highest mountain ranges are gradually succumbing to the geological surveyor; the heart of Africa is giving up to us its secrets and its treasures, and plans of all the desert places of the earth are being made and tabulated. The bottom of the deep sea was until quite r

Our knowledge of the natural history of the deep seas may be said to have commenced not more than fifty years ago. There are, it is true, a few fragments of evidence of a fauna existing in depths of more than a hundred fathoms to be found in the writings of the earlier navigators, but the methods of deep-sea investigation were so imperfect in those days that naturalists were disposed to believe that in the abysses of the great oceans life was practically non-existent. Even Edward Forbes just bef

It is not surprising that the naturalists of the early part of the present century could not believe in the existence of a fauna at the bottom of the deep seas. The extraordinary conditions of such a region—the enormous pressure, the absolute darkness, the probable absence of any vegetable life from want of direct sunlight—might very well have been considered sufficient to form an impassable barrier to the animals migrating from the shallow waters and to prevent the development of a fauna peculi

In the study of the geographical distribution of terrestrial animals one of the great difficulties met with is the impossibility of defining exactly the limits of the regions into which we divide the surface of the earth. In a general way we recognise that there is an Australian region, an Ethiopian region, &c.; but, when we come to discuss the exact position of the frontier lines that separate these regions from their neighbours, we find all kinds of difficulties to overcome and inconsi

The general characters presented by animals living in deep water may be considered under several headings. The most important are those that are directly or indirectly related to the fact that the animals live either in total darkness or in the faint and probably intermittent light emitted by phosphorescent animals; namely, the colour of the skin and the peculiarities of the eyes. The colours of the skin of the deep-sea animals vary to a very remarkable extent in the different groups. It cannot

The most important, but perhaps somewhat disappointing, result of the deep-sea researches of recent years has been to prove that the abysmal fauna does not possess many very extraordinary forms. It seemed probable, before the dispatch of the ‘Challenger’ expedition, that when the dredge and the trawl should be successfully employed in depths of over 2,000 fathoms, a new and remarkable fauna would be brought to light. Some naturalists thought it even possible that, not only would many genera be f

It has not been my intention in this volume to confine my attention to the truly abysmal forms, but rather to consider all those animals living in deep water that show any characters strikingly different from their relatives living in shallow water. The term deep water is, after all, only a relative one. To one accustomed only to shore collecting, ten fathoms is deep water, while on the other hand, to such naturalists as those on board the ‘Challenger,’ who are accustomed to dredge in all seas,

The deep-sea fauna seems to be particularly rich in marine Arthropoda, many curious and interesting forms being brought up with almost every haul of the dredge. The Arthropoda, too, being very highly organised animals, afford interesting and instructive examples of the effect of abysmal life in the modification of the sense organs and the production of varieties specially modified for the conditions of the struggle for existence in their strange habitat. Concerning the groups of Ostracoda and Co

Of all the groups of animals that constitute the deep-sea fauna, the fish show the greatest number of peculiarly abysmal characters. Being much more highly differentiated than the invertebrates, they possess more organs liable to undergo modifications of colour, size, and structure, and consequently we are able to point to a great many more features characteristic of deep-sea fish than we can do in any other group of animals. The first point that calls for remark in the consideration of the fish