Archive image from page 636 of The depths of the ocean;. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceange00murr Year: 1912 PELAGIC ANIMAL LIFE 599 Only exceptionally, and chiefly in the Antarctic, forms were found be- tween 1500 and 1000 metres that in warm waters live at the surface. The Salpae are individually most abundant in warm water, and in the Atlantic we do not find a single species which is peculiar to the area north of lat. 45° N. Ap
Archive image from page 636 of The depths of the ocean;. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic depthsofoceange00murr Year: 1912 PELAGIC ANIMAL LIFE 599 Only exceptionally, and chiefly in the Antarctic, forms were found be- tween 1500 and 1000 metres that in warm waters live at the surface. The Salpae are individually most abundant in warm water, and in the Atlantic we do not find a single species which is peculiar to the area north of lat. 45° N. Apstein tells us that three species have been found in the northern region, viz. Salpa fusiforntisy S. mucronata, and 5. zonaria, but they really belong to warm waters and have been carried north by currents (see Fig. 447). The genus Cyclosalpa comprises typical warm-water forms. The genus Doliolum is also, according to Neumann's1 treatise on the ' Valdivia' collection, chiefly a warm-water form exceedingly sensitive to changes of temperature. Doliolum krohni, D. tritonis, Fig. 447.—Distribution of Salpa fusiformis. (From Apstein.) D. miilleri, and D. gegenbauri are the species which go farthest north in the Atlantic. The genus Pyrosoma (Fig. 448) has from the earliest days of oceanography attracted the interest of man, to a great extent on account of the strong phosphorescent light emitted, the name meaning ' fire-animal.' The individuals are aggregated into cylindrical colonies, which may attain an enormous size (several yards long). Some occur in the surface-waters, some in deep water. In the narrative of the 'Challenger' cruise, Sir John Murray, describing the voyage from the Bermudas to the Azores, writes as follows :—' On the 25th (of June) a very large colony of a new species of Pyrosoma was captured in the trawl. The cylinder was 4 feet 2 inches in length and 10 inches in diameter, closed at one end, and as in the 1 Neumann, Wiss. Ergeb. Valdivia-Expedition, Bel.
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