SEA LIFE. 8. Pectanthis asteroides. 7. Actinotheca pellucida. 6. Chondrocladia virgata. 5. Sclerothamnus Clausii. 15. Psychropotes buglossa. 16. Styracaster spinosus. 24. Eurypharynx pelecanoides. ilis. 13. Euphronides Talismani. 14. Peniagone rosea. 23. Eustomias obscurus. 22. Boltenia pedunculata. Nymphon robustum. Lacrurus globiceps. 28. Melanocetus Johnstoni. 29. Stomias boa. often in large patches of striking contrast. No deep-sea fishes above about five feet in length have been taken. This is not regarded as evidence that they do not grow longer, the fact that the mouths of the largest beam-trawls in use are only about II by 2 or 3 feet probably having something to do with the matter. The dredge or beam-trawl commonly used is a form of big bag-net, of 20 to 25 feet in length, that is weighted and dragged along the bottom. As many as 800 fishes have been brought up in a single haul with such a dredge, from a depth of 1,770 fathoms, in Bering Sea. Four or five hours are required to dredge at such a depth. The deepest haul on record at which animal life was obtained was made by the Albatross of the United States Fish Commission, near the Tonga Islands, the depth being 4,173 fathoms. Ten hours elapsed from the time the dredge went overboard till it was brought again to the deck. The tangle is a device used for bringing up specimens of fauna or anything it can catch. This consists of an iron bent in the form of an inverted V and having frayed rope attached to it. During recent years gill-nets have been used at a depth of a mile, and traps and trawl-lines have also been sunk to considerable depths. The first reliable sounding at a great depth is credited to Capt. Sir James Clark Ross, who in 1840 sounded 2,677 fathoms on the west coast of Africa. Subsequent soundings were reported as deep as 7,000 fathoms, but as these were made with the old-fashioned clumsy apparatus that tended to drift tremendously, and as they do not agree with modern soundings, they are not credited. In 1854 J. M. Brooke of the United States navy, suggested the employment of a dropped weight in deep-sea sounding, and this was found to assist matters so much that it has remained in use ever since. The first attempts to substitute wire for rope were not very satisfactory, owing to the too great thickness and weight of the wire used. When steel piano-wire of great tensile strength was brought into use and weighted with a 60-pound shot, arranged to be dropped, it was found that the soundings were made with a close approach to accuracy, and at much greater speed in much less time than before. In 1872 there was invented the cylinder sounding machine in which a cannon-ball was used for the sinker, the ball having a hole bored through it, in which was placed a metal tube or small cylinder. When the weight descended into the muddy bottom, the tube was filled with mud, and a device closed it, at the same time releasing the ball. Another device originated later consists of two hemispherical cups, normally hinged so as to be apart. When the weight strikes the bottom it brings the cups together, so that they grasp whatever is in the way. The wire used in soundings weighs about 14 pounds to the mile, and very ingenious reeling-machines have been devised for handling it. The first difficulty to be overcome was the roll of the ship, which tended to jerk the line. This is compensated for, and a friction device is adjustable so as to balance the weight of wire, etc., The testing o the current-mete is hung on a wh down. A screv with the current registering the which registrati The older device depended upon t floats to note th lower currents. When it was peratures by depths it was fo neous, apparently sure. Miller an thermometer tha culty, but it serv and minimum te bra improved on in reversed posit ing it back to the test. The t column of mercu rect temperature A most inger temperature of a from the deck o Sir William Sie ture on the Wh electric resistanc sel of water is h balances, and in the vessel i low. The appar for ordinary us into the depths pressure, their the depths to wh The deepest that of the Tusc Commission, wh coast of Japan, est sounding wa the Admiralty fathoms. In 18 5,155 fathoms n the record. Th 1900, when the Nero found a de Other deep soun of the United located a depth and of the Bla Survey, which s Rico, this being Atlantic Ocean found north of tends to confirm Arctic Ocean Three Cruises Sea Sounding a Sea Exploration Deep-sea Li line between de water, owing to tain species live DEEP-SEA LIFE of New England (Cancer irroratus) ranges to a depth of nearly 500 fathoms. The Challenger Expedition selected as defining the deep-sea fauna, a depth of 100 fathoms, others have taken 500 fathoms as marking its upper boundary, and still others a depth of 1,000 fathoms. A knowledge of this life is only obtainable by means of apparatus which will bring to the surface specimens from these great depths. The chief of these instruments, aside from the sounding lead which is very inadequate for this purpose, are dredges, tangles, and trawls, of which various patterns have been devised but which may be described in general terms as follows: The dredge consists of a rectangular frame-work of iron, one edge being sharpened or fitted with rake-like teeth to plow or scrape the bottom, while a net or bag fastened to the frame serves to hold the material collected and to bring it to the surface. This is best adapted for obtaining forms which live, attached to, or burrowing in, the ocean bottom. The trawl is a similar net so arranged as to be drawn just above the bottom and is valuable for collecting fishes which swim freely through the water. The tangle consists of large masses of unraveled rope, usually attached to a chain, which, sweeping over the ocean floor, entangles spiny forms like shrimps, starfish, sea urchins, as well as forms like hydroids and sea anemones, with numerous tentacles. Somewhat different is the Tanner net. This is so arranged that it can be sent down close to any desired depth, opened there, drawn through the water and then closed again before being drawn to the surface. By means of this the fauna of any desired depth can be collected without danger of admixture with forms from other depths. Details of the construction of these and many other pieces of collecting apparatus may be found in Agassiz, Three Cruises of the Blake'; Sigsbee, 'Deep-Sea Sounding and Dredging) (U. S. Coast Survey, 1880), and in the publications of the United States Fish Commission. Although the dredge had previously been in use in the oyster and scallop fisheries it was first employed for scientific purposes (in moderate depths) by the Danish naturalist, Otto Fabricius Müller, 1750. (In America it was first used by Henry Wheatland of Salem, Mass.) Owing to faulty observations and to a belief that life could not exist in the greater depths of the ocean on account of the great pressure and the absence of light it was long thought that animals were not to be found at depths greater than 500 fathoms. This view disregarded the fact that Ross and Sabine, 1829, claimed to have obtained living animals from a depth of about 2,000 fathoms in Baffin Bay. Little by little evidence from sounding lines and submarine cables was accumulated which tended to overthrow this belief, but its complete disproval was accomplished by the dredgings of the United States Coast Survey in the Strait of Florida, 1867, when animals were found to be abundant at a depth of 700 fathoms. This was followed, 1869, by the expedition of the English ship Porcupine, which made successful casts of the dredge in 2,435 fathoms of water. Since that time numerous deep-sea dredgings have been conducted by the various governments, the most noticeable being the cruises of the English ship Challenger, the American Blake and Albatross, the French Travailleur and Talisman, the Russian Minineh, the Swedish Vanadis, the Dutch Barents Expedition, the German Tiefsee Expedition, and the explorations of the Prince of Monaco. The results of all these go to show that life, even of highly organized types, occurs in the greatest depths of the ocean. Since the dredge, tangles and trawls can touch but a minute portion of the deeper parts of the ocean bottom we have, as yet, but an inadequate knowledge of the benthal or abyssal fauna for details of which the reader should consult the reports of the various expeditions previously mentioned. In general the following remarks may be made. The greater the depth, the fewer the species present. Thus in the collections of the Challenger, 2,050 species were taken in depths between 100 and 500 fathoms; 710 between 500 and 1,000; 600 between 1,000 and 1,500; 500 between 1,500 and 2,000 fathoms; 340 between 2,000 and 2,500, and 235 from depths greater than 2,500 fathoms. Again the results of the same expedition show that the number of individuals also decreases with the depth. In depths of over 1,000 fathoms the dredge rarely captured over 10 or 15 specimens of any one species, while in lesser depths hundreds of a kind are common. The majority of the abyssal forms probably live on the surface ooze of the bottom and the minute organisms occurring in it, while these forms are in turn preyed upon by larger rapacious forms. A prominent feature of these is the frequent occurrence of phosphorescent organs which probably serve as a lure. Some are blind, some are provided with very large eyes, and it seems certain that all the light in the greater depths of the sea is produced by the phosphorescent organs. Another feature is the large size of some of the individuals. Thus while the shallow water species of the hydroid Monocaulus reach a length of but two or three inches, the deep-sea form is three feet long. It was hoped that the deep-sea fauna would reveal living representatives of extinct groups, but this hope was not realized, nothing having been found older than the horse-shoe crab (Limulus) the brachiopods, Ceratodus, the Port Jackson sharks and the Dipnoi of shallower or fresh waters. Taking now the separate groups of living forms occurring in the deeper waters the following general remarks may be made: Plants are extremely rare and include only a few minute and inconspicuous forms. Even the lower Alga (seaweeds) so common in shallower waters are lacking. Among the sponges the so-called glass sponges (Hexactinellide) are most abundant, some of the species being enormous (3 or 4 feet in diameter). The Calenterata are represented by the giant Monocaulus, already mentioned, and by a few jellyfish and corals. All groups of Echinoderms occur, most noticeable being the comparatively large number of crinoids and of holothurians, many of which are strange in structure and bizarre in outline. The Arthropoda consists largely of prawns, schizopods and isopods, some of the latter being gigantic in size, and the strange sea spiders (Pycnogonids), some having slender legs extending a foot or more from the body. Crabs are rare, as are also annelids and molluscs, while a few brachiopods (and these not of the oldest types) occur. Possibly the most interest |