Latitude 29 degrees 26 minutes south; longitude 101 degrees 32 minutes
east.

We caught several small shells (Janthina exigua) this afternoon:
Illustration 9 represents one of them, with the string of air bubbles
attached, by means of which they swim on the water. They appear not to be
able to free themselves from this mass of bubbles: every shell I have yet
found floating in the Indian Ocean possesses these bubbles in a greater
or less degree; they were of a purple colour. I have seen the common
garden snail in England emit a nearly similar consistency: they also emit
a blue or purple liquid, which colours anything it touches.

The animals of the barnacles (Pentalasmis) attached to these shells
assume their purple colours, while the shell remains nearly pure white.

This afternoon we caught an animal (Glaucus, Illustration 10) I had not
before seen. It seemed to represent the order reptilia in the Mollusca,
being sluggish in movement, its eyes distinct, sensitive to the touch,
its head much resembling a lizard in appearance, and having a very strong
unpleasant smell when taken out of the water. During the hour I observed
it in a bucket it remained sluggishly floating on the top, and
occasionally swimming by moving its arms slowly along the surface. The
first three that I saw pass the vessel I imagined to be feathers floating
on the water.

Its description is as follows:

Length from head to tail, a c 1.8 inches.
Length from head to root of tail, a b 0.85 inches.
Length from head to first arm 0.2 inches.