No. 418.] NOTES ON LIVING. NAUTILUS, 827 
sienna, and yellow ochre, and that the pigment has then been 
carelessly wiped away, leaving the warty prominences in white 
relief. Nowhere are observed the characteristic chromato- 
phores of the dibranch. The only pigmentation which may 
further be noted is on and around the eye, and in the creases 
between the thickened proximal portions of the oral tentacles, 
also on the edge of the mantle, margining the oral aperture ; 
from this the shell itself receives an inky border, which is 
continued from the blackened portion of the coil around the 
entire aperture. This line measures about 2mm. in width 
and can be detected from the outer surface of the shell; it 
does not appear, however, in shells which have been carelessly 
cleaned. ^ 
Nautilus, as far as my experience goes, lives but a short time 
in confinement, twenty hours being the longest time I was able 
to keep one alive. And even from the beginning the animal 
was evidently not at its best. It is true that the conditions 
under which I observed them were unfavorable, for in no case 
were specimens brought me which had been confined less than 
three hours in a water bucket. And the best aquarium I could 
improvise was a tank which held only about two hundred liters 
of water. Changing the water at frequent intervals had little 
effect in keeping the animals alive. I soon found that it was 
difficult to know just when the animal did die, for it retains a 
very lifelike position. This I discovered as follows : with 
a view of finding whether at any time movements became 
more active I caused my helper to watch a specimen through 
out the night, the man to call me in case it showed change of 
Position or any peculiar behavior. In the early morning I was 
told that the animal had shown no movements, a statement I 
soon had little reason to doubt, for I found my Nautilus dead. 
On returning it to the water I observed that it floated, retain- 
ing, however, its customary position ; and so it stayed 1n spite 
of my efforts to cause it to sink. This is the only case 1M 
which I observed a specimen remain at the surface ; and the 
thought suggested itself that it was from such floating speci- 
mens that the idea originated that Nautilus was more OF less 
à surface form. 
