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 by them resembles that which would be caused by the passage of a rapid succession of electric shocks, rather than any other I am acquainted with.
GEOLOGICAL OBSERVATIONS AT ST.

HELENA.
July 21.
After visiting Longwood and Napoleon's tomb we rode to Flagstaff Hill to search for fossil shells.