I observed their motions from a boat at first, and afterwards when they were in a glass of water.
I counted the number of times they expelled water in a given time when swimming, and found the mean of several observations by a chronometer to give ten strokes in twelve and a half seconds.
We caught again many little animals which I had found on the 15th of October 1837; south latitude 37 degrees 28 minutes, east longitude 21 degrees 19 minutes; they were shaped like an octagonal crystal, terminating in a point, containing a brilliant blue colouring matter, they were about 0.4 inches in length, and were, when undisturbed, arranged in long strings, only the length of a single animal in thickness, and of the breadth of two of them abreast; they swam with the blue-pointed ends downwards, which then looked at a distance like the legs of a caterpillar, and the long string somewhat resembled a long gelatinous band in appearance as it passed through the water; but directly it was touched the animals separated themselves from one another.

These strings were sometimes seen several feet in length.
We caught large quantities of these animals at one time, and found: The temperature of the water 65 degrees Fahrenheit.
The temperature of the air 75 degrees Fahrenheit.
The temperature of the animals 66 degrees Fahrenheit.
We caught also a fish (Orthogariscus) which the seamen called a devil-fish.
The length of it was 6 feet 2 inches.
Breadth from fin to fin 3 feet 6 inches.
Length from tip of nose to pectoral fin 2 feet.
Thickness through the breast 1 foot 6 inches.
This fish was infested about its nose with a kind of parasite (Lernaea) having two long thin tails.

The sailors stated that these animals frequently cause large sores about the nose of the fish, and that when suffering from this, it will allow the sea-birds to sit on it, and peck away at the affected part.

The habit of the fish is to swim during calms with one of the hind fins out of water, and it is then harpooned from a boat.

I have myself seen petrels perched upon them; and directly one of these fish was hoisted on board the sailors looked for the parasites and found them.