312 THE OCEAN WORLD. 
is also found in the same sea. It is a long bluish cylinder shape 
bristling with bracts, at the base of each of which is the abode of a 
polyp, a citizen of this moving republic, which is attached to its 
colleagues by means of its gelatinous envelope, an alliance imposed 
by inexorable Nature. 
Another species, P. atlanticum, was discovered by Péron and 
Lesueur in the equatorial seas. 
These curious Tunicates grow in such a manner as to constitute a 
long fine cylindrical tube, closed at one end and open atthe other. By 
the contraction and dilatation of the mass of beings, this great cylinder 
swims slowly through the open sea, lighting up the ocean with its 
phosphorescent light, shining through the water like a glowing fire. 
Mr. Bennett thus describes the phenomenon presented by ‘these 
creatures. ‘On the 8th of June, being then in lat. 30° S. and 27° 
5° W. long., having fine weather and a fresh south-easterly trade-wind, 
and the thermometer ranging from 78° to 84°, late at night the mate 
of the watch called me to witness a very unusual appearance in the 
water. This was a broad and extensive sheet of phosphorescence 
extending from east to west as far as the eye could reach. I 
immediately cast the towing net over the stern of the ship, which 
soon cleaved through the brilliant mass, the disturbance causing 
strong flashes of light to be emitted, and the shoal, judging from the 
time the vessel took in passing through the mass, may have been a 
mile in breadth. On taking in the towing-net, it was found half filled 
with Pyrosoma atlanticum, which, shone with a beautiful pale greenish 
light. After the mass had been passed through by the ship, the 
light was still seen astern, until it had became invisible in the 
distance, and the ocean became hidden in the darkness as before 
this took place. 
“The second occasion of my meeting these creatures was in a 
high latitude, and during the winter season. It was on the roth ot 
August, the weather dark and gloomy, with light breezes from north- 
north-east, in lat. 40° 30’ S., and 138° 3’ E. long., at the western en- 
trance to Bass’s Straits, and about eight o’clock p.m., when the ship’s 
wake was perceived to be luminous, while scintillations of the same 
light were abundant all round. To ascertain the cause, I threw the 
towing-net overboard, and in twenty minutes succeeded in capturing 
several Pyrosoma, which gave out their usual pale green light ; and 
it was, no doubt, detached groups of these animals which were the 
occasion of the light in question. The beautiful light given out by 
these molluscans soon ceased to be seen ; but by moving them about 
it could be reproduced for some length of time after. The luminosity 
