146 ARTHUR WILLEY. 
not having been previously published.1. From the photograph 
it will be seen that in swimming the animal elevates itself to 
such an extent that the eyes are raised above the free margin 
of the mouth of the shell. As to its movements on the sur- 
face of the water, there is very little to add to the excellent 
account given by the late Professor Moseley in his ‘ Notes by 
a Naturalist on H.M.S. Challenger.’ 
I can emphatically confirm Moseley when he says that “ it 
is probably a mistake to suppose that it ever comes to the 
surface voluntarily to swim about.’ Nevertheless a Nautilus 
is not necessarily ruined by being brought up from the bottom 
in a fish basket. If liberated within a reasonable time it is 
capable of returning to its natural habitat. I have proved this 
experimentally. 
When freshly captured Nautili are placed in aquaria they 
rise to the surface and sink to the bottom with the greatest 
facility. The rising to the surface, according to my observa- 
tions, is effected solely by the muscular activity of the animal, 
and is in no way dependent on any physical modification of 
the gas in the air-chambers. ‘The presence of the latter 
renders the shell extremely light and buoyant, so that it is, 
under normal circumstances, completely under the control of 
the muscles of the animal. I say ‘under normal circum- 
stances” advisedly, because there is one thing which the 
Nautilus cannot do, namely, turn upside down. It is neces- 
sary to insist on this, because Moseley gives a translation of 
the account given by Rumphius at the beginning of last 
century, which, I regret to say, so far as my experience has 
gone, is very wide of the mark. Always remembering that 
Rumphius was the first to demonstrate the cephalopodous 
character of the pearly Nautilus, the suspicion is forced upon 
me that he derived his account of its habits from the narrative 
of an ill-informed and imaginative Malay fisherman. Natives 
are so often remarkably well informed about the habits of 
animals, that the above supposition can by no means be taken 
as conveying a reproach to the old master. 
1 This photograph is reproduced as Fig. 24 at the end of this article. 
