d by three shields, and there was only one leg on
each side. I could not make out any tentaculae or antennae.

I was much struck by a curious circumstance today. As we caught a great
many gelatinous animals I thought this a good opportunity of taking their
temperature, which, after an observation so carefully made that no error
could occur, was found to be 66 degrees 5 Fahrenheit, the temperature of
the air at the same time being 74 degrees. The temperature of the water
was now taken and was found to be 2 degrees 5 minutes more than that of
the animals; thus giving these animals a temperature lower than that of
the fluid in which they were immersed. I conceived that some error must
have been made in the temperature of the water, it was therefore taken
again and found to be 69 degrees as before; this appeared to me so
remarkable that I drew up a table of all the experiments which had been
made on this subject, the result of which is that the mean temperature of
these kinds of animals appears to be 64 degrees 9 minutes Fahrenheit; and
that the greatest variation in excess is 1 degree 7 minutes; and in
defect 2 degrees 9 minutes Fahrenheit. Is it possible, then, that an
animal can live in a fluid, the temperature of which is constantly
varying, and preserve nearly a mean heat?

In the following tables I have entered every experiment but one which was
made on the 17th of June, and in which I believe the animals to have been
kept too long out of water.

(Experiments to determine the temperature of gelatinous animals which
inhabit the sea:

Experiments to determine the temperature of shellfish inhabiting the open
ocean:)

This last experiment was made from a sickly specimen which had been kept
for some time in the water: the temperature of water above given is for
that in which this animal was kept.

We caught again today many animals of the same family (Glaucus) as those
of which a description is given in the journal for the 17th of June.

Also many shrimp-like animals (Alima) the bodies of which were divided
distinctly into an interior and posterior portion; all the shrimp-like
animals which we have caught whose bodies are thus divided swim by
doubling up the posterior part close to the anterior, and then giving a
stroke with great rapidity outwards. These little animals are very
susceptible, and when they have been in the least injured their limbs
remain in so constant a state of tremor that the motion communicated