POLYZOA AND TUNICATA. 
237 
serpentine movements. The genus Pyrosoma contains ani- 
mals aggregated in another manner. These are lengthened 
Ascidiaus, united to each other so as to compose a long 
free tube, open at one extremity and closed at the other. 
This is also an oceanic genus, and is remarkable for being 
vividly luminous, the light displaying the most goi-geous 
and varied hues. We shall close this chapter with an 
extract from Mr Bennet’s “Wanderings,” in which he 
records his own observations of these interesting animals. 
“ On the 8th of June, being then in lat. 0° 30' south, 
and long. 27° 5' west . . . 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, con- 
sidered to be breakers. On arriving upon the deck, this 
was found to be a very broad and extensive sheet of phos- 
phorescence, extending in a direction from east to west, 
as far as the eye could reach. Tho luminosity was con- 
fined 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 tho ship, as we ap- 
proached near 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 tho mass, may have been a mile in 
breadth. The passage of the vessel through thorn in- 
creased the light around to a far stronger degree, illumi- 
nating the ship. On taking in the towing-net, it was 
found half filled with Pyrosoma ( Atlantic tyfi ?'), which shone 
with a beautiful pale-greenish light, and there were also 
