SOMETHING ABOUT JELLY-FISHES. 247 
to hold them, may be filled at once, as too frequent 
changes destroy them. 
Some species are very hardy, and may be kept alive 
for weeks, while others live only a few hours, gradually 
diminishing in size till they appear to melt away in the 
water. 
Among the more common forms met with on our coast 
is the Pleurobrachia (Plate 8, Fig. 8). Words fail in 
describing the beauty and singularity of this Jelly-fish. 
Conceive a globular body the size of a walnut or larger, 
but perfectly transparent, having eight bands of rapidly 
Vibrating fringes surrounding the body, running from one 
pole to the other like the ridges on a walnut, and two 
thread-like appendages, festooned with hundreds of shorter 
threads, trailing out behind the body like the tail of a 
‘comet, and you have a general idea of this Jelly-fish. 
The zones of vibrating fringes act like so many little 
oars, and impel the body through the water. At times, 
only the fringes on one side are in motion, and then the 
body rotates in the water like a vital globe. Anon, the 
different zones alternate in action, and the body describes 
4 spiral course in the water. The most beautiful pris- 
matic hues are exhibited when these fringes are in 
motion, and these brilliant changing colors often lead to 
their detection in the water. The long thread-like appen- 
dages, already mentioned, are the most wonderful portion 
of the structure of this Jelly-fish. They are lined with 
hundreds of smaller threads which start at right angles. 
from the main threads, and are all of the extremest te- 
nuity. The distance these appendages can be projected 
from the body, the instantaneous manner in which they 
are, drawn within the body, and the perfect control the 
animal manifests in their movements seems incredible, 
