Among shore-dwellers generally there obtains an idea that the ocean, except in the immediate vicinity of land, is an awful solitude, its vast emptiness closely akin to the spaces above. But while admitting fully that there is little room for wonder at such a speculative opinion, it must be said that nothing could well be farther from the truth. Indeed, we may even go beyond that statement, and declare that the fruitful earth, with its unimaginable variety and innumerable hosts of living things, is, when compared to the densely populated world of waters, but a sparsely peopled desert. A little knowledge of the conditions existing at great depths, may well make us doubt whether any forms of life exist able to endure the incalculable pressure of the superincumbent sea; but leaving all the tremendous area of the ocean bed below 200 fathoms out of the question, there still remains ample room and verge enough for the justification of the statement just made.  
Nothing has ever excited the wonder and admiration of naturalists more than this prodigious population of the sea—these unthinkable myriads of hungry things which are shut up to the necessity of preying upon each other since other forms of food do not exist.320 The mind recoils dismayed from a contemplation of their countlessness, as it does from the thought of timelessness or the extent of the stellar spaces, shrinkingly admitting its limitations and seeking relief in some subject that is within its grasp. But without touching upon the lower forms of life peopling the sea, and so escaping the burden of thought which the slightest consideration of their myriads entail, it is possible to note, without weariness, how, all over the waste spaces of a remote and unhearing ocean, fish of noble proportions and varying degrees of edibility disport themselves, breeding none know where, and revealing their beauties to the passing seafarer as they gather companionably around his solitary keel. Excluding all the varied species of mammals that form such an immense portion of the sea-folk, it may roughly be said that the majority of deep-sea fish belong to the mackerel family, or Scombridæ. They possess, in an exaggerated form, all the characteristics of that well-known edible fish that occasionally gluts our markets and gladdens the hearts of our fishermen.
 
One of the least numerous, but from his size and prowess probably the monarch of all sea fish, is the sword-fish, Xiphias. This elegant fish attains an enormous size, specimens having been caught weighing over a quarter of a ton; but owing to the incomparable grace of its form, its speed and agility are beyond belief. It is often—in fact, generally—confounded with the “saw-fish,” a species of shark; the principal reason of this confusion being the great number of321 “saws” or beaks of the latter, which are to be found in homes about the country. Yet between the sword of the Xiphias and the “saw” of the Pristiophoridæ there is about as much similarity as there is between the assegai of a Zulu and the waddy of a black-fellow. The one weapon is a slender, finely pointed shaft of the hardest bone, an extended process of the skull, about two feet long in a large specimen. Impelled by the astounding vigour of the lithe monster behind it, this tremendous weapon has been proved capable of penetrating the massive oaken timbers of a ship, and a specimen may be seen in the Museum of Natural History at South Kensington, at this present time, transfixing a section of ship’s timber several inches in thickness. The “saw,” on the other hand, is, like all the rest of a shark’s skeleton, composed of cartilage, besides being terminated at the tip by a broad, almost snout-like end. Unlike the round lance of the sword-fish, the “saw” has a flat blade set on both sides with sharp teeth with considerable gaps between them. As its name and shape would imply, it is used saw-wise, principally for disembowelling fish, for upon such soft food the saw-fish is compelled to feed owing to the shape of his mouth and the insignificance of his teeth. Thus it will be seen that apart from the radical differences between the two creatures, nothing being really in common between them, except that they are both fish, there is really no comparison possible between “saw” and “sword.” Fortunately for the less warlike inhabitants of the deep sea, sword-fish are not numerous, there are none to cope with them or keep their322 numbers down if they were prolific. Sometimes—strange companionship—they join forces with the killer whale and the thresher shark in an attack upon one of the larger whales, only avoiding instinctively that monarch of the boundless main, the cachalot.
 
Next in size and importance among deep-sea fish, excluding sharks, about which I have said so much elsewhere that I do not propose dealing with them here, is the albacore, tunny or tuña, all of which are sub-varieties of, or local names for the same huge mackerel. They abound in every tropical sea, and are also found in certain favourable waters, such as the Mediterranean and Pacific coast of America. Like the sword-fish their habits of breeding are unknown, since they have their home in the solitudes of the ocean. But they are one of the fish most frequently met with by seafarers, as, like several others of the same great family, they are fond of following a ship. A sailing ship that is, for the throb of the propeller, apart from the speed of the vessel, is effectual in preventing their attendance upon steamers, so that passengers by steamships have few opportunities of observing them. But in sailing vessels, gliding placidly along under the easy pressure of gentle breezes, or lying quietly waiting for the friendly wind, ample scope is given for study of their every-day life. Very occasionally too, some seaman, more skilful or enterprising than his fellows, will succeed in catching one by trolling a piece of white rag or a polished spoon with a powerful hook attached. Yet such is the vigour and so great is the323 size of these huge mackerel, some attaining a length of six feet and a weight of five hundred pounds, that their capture from a ship is infrequent.
 
In size, beauty, and importance, the “dolphin” easily claims the next place to the albacore. But an unaccountable confusion has gathered around this splendid fish on account of his popular name. The dolphin of mythological sculpture bears no resemblance either to the popularly named dolphin of the seaman and the poets, or the scientifically named dolphin of the natural histories, which is a mammal, and identical with the porpoise. One thing is certain, that no sailor will ever speak of the porpoise as a dolphin, or call Coryphena hippuris anything else. Of this lovely denizen of the deep sea, it is difficult to speak soberly. Even the dullest of men wax enthusiastic over its glories, feeling sure that none of all beautiful created things can approach it for splendour of array. I have often tried to distinguish its different hues, watching it long and earnestly as it basked alongside in the limpid blue environment of its home. But my efforts have always been in vain, since every turn of its elegant form revealed some new combination of dazzling tints blending and brightening in such radiant loveliness that any classification of their shades was impossible. Then a swift wave of the wide forked tail-fin would send the lithe body all a-quiver in a new direction, where, catching a stray sunbeam it wo............