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Show 1899.] ON A ZOOLOGICAL EXPEDITION TO THE SOUTH SEAS. 7 1. General Account of a Zoological Expedition to the South Seas during the years 1894-1897. By A R T H U R WILLEY, D.Sc. Lond., Hon. M.A. Cantab. [Eeceived January 16, 1899.] The main 'object of my recent journey to the South-west Pacific was the investigation of the life-history of the Pearly Nautilus. My first destination was the Island of N e w Britain (Neu-Pommern) in the Bismarck Archipelago, as this had already become known as a locality where living Nautiluses could be obtained in abundance. The principal difficulties which had to be coped with were owing to the comparatively deep water-50 to 70 fathoms-in which Nautilus pompilius lives. It is only to be caught at night-both in Blanche Bay and in Talili Bay, on opposite sides of the Gazelle Peninsula-in native fish-traps baited with small fish. After finding the tracts where Nautiluses congregated in shoals at night, I would, on the following morning, go over the same ground with the dredge. Almost always the dredge would come up full of pumiceous fragments. In fact I came to the conclusion in N e w Britain, which I afterwards confirmed in the Loyalty Islands, that the feeding-ground is not the breeding-ground of the Nautilus-or, in other words, that the Nautilus migrates in shoals nocturnally from deeper into shallower water in quest of food. The Nautilus will eat any animal-food which is offered to it, from a fowl to a sea-urchin, and from a langouste to a shrimp, but its natural food consists chiefly of small Decapod Crustacea. W h e n attacking a shrimp, for example, the Nautilus dart i forward with great rapidity, and enclosing the victim within its tentacular complex seizes it between its powerful beak-like jaws. It can protrude its body by action of protractor muscles far beyond the mouth of the shell, but it only does this when occasion demands. W h e n normally swimming, the body is slightly raised as to completely expose the eyes above the level of the margin of the shell, and to allow free entrance for the water into the mantle-cavity and exit through the cleft siphon. Like all the other Cephalopods, Nautilus swdms backwards with considerable speed. It holds the shell, when swimming, in one position only, namely with the spire and with the mouth of the shell directed upwards, as shown in the photograph here exhibited. Nautilus is incapable of capsizing its boat as described by Rumpbius. After spending the best part of a year in N e w Britain, during which I made new observations upon the vascular system and branchial sense-organs, I determined to change my base, and accordingly proceeded to the Eastern Archipelago of British New Guinea. Meanwhile, however, I had made a prospecting journey to N e w Hanover, where I found the natives baling out their canoes with Nautilus-shells. I made no further progress during the five months I spent in N e w Guinea so far as Nautilus is concerned, |
