SWIMMING ASCIDIANS. 323 
in the sea by means of the combined contractions 
and dilatations of all the individual animals which 
compose it. The branchial orifices are pierced 
near the points, and the anus opens into the inte- 
rior cavity of the tube. Thus, says Cuvier, 
one may compare a Pyrosoma to a great number 
of stars of Botrylli, strung one after the other, but 
the whole of which would be moveable. 
Mr. George Bennett, in his interesting ““ Wan- 
derings in New South Wales,” after some valuable 
remarks on the luminosity of the ocean, proceeds 
as follows :— 
“On the 8th of June, being then in latitude 30’ 
south, and longitude 27° 5’ west, having fine wea- 
ther and a fresh south-easterly trade-wind, and the 
range of the thermometer being from 78° to 84°, late 
at night, the mate of the watch came and called 
me to witness a very unusual appearance in the 
water, which he, on first seeing it, considered to 
be breakers. On arriving upon the deck, this was 
found to be a very broad and extensive sheet of 
phosphorescence, extending in a direction from 
east to west, as far as the eye could reach. The 
luminosity was confined to the range of animals in 
this shoal, for there was no similar light in any 
other direction. I immediately cast the towing- 
net over the stern of the ship, as we approached 
nearer the luminous streak, to ascertain the cause 
of this extraordinary and so limited phenomenon. 
The ship soon cleaved through the brilliant mass, 
from which, by the disturbance, strong flashes of 
light were emitted ; and the shoal, judging from 
the time the vessel took in passing through the 
mass, may have been a mile in breadth. The 
passage of the vessel through them increased the 
