CLASS SCYPHOZOA 
THE LARGE JELLYFISHES 
HERE is perhaps no marine animal which excites more wonder 
T than the jellyfish. Its transparency, its graceful rhythmical 
movements, its long streaming tentacles, the variety and eccen- 
tricity of its form, and often of its color, attract attention, and 
one naturally desires to know something of its life-history. Jelly- 
fishes are also called meduse, because their long appendages sug- 
gest the locks of the Gorgon ; acalephs, on account of their stinging 
or nettle-like properties; and sun-jellies, sea-blubbers, etc., be- 
cause they float upon the surface during the warmest part of the 
day, when the sun is high. The name jellyfish is inappropriate, 
since the animal in no way resembles a fish except in the fact 
that it swims; but it is, nevertheless, the commonest name. 
Jellyfishes vary in size from that of a pinhead to six or seven 
feet in diameter. They differ in the number, size, and position 
of the tentacles, the number of the radial canals, the form of the 
manubrium, the position of the egg-sacs, ete.; but the general 
plan of the internal structure is the same in allspecies. In shape 
they are compared to a mushroom. From the center of an um- 
brella-like top falls a central organ like the stalk of a mushroom. 
It is called the manubriwm and is the mouth and stomach of the 
animal. 
From the top of the manubrium radiate straight or branched 
tubes, which are connected with a canal which runs around the 
whole margin of the umbrella. Extending around the inner 
circumference of the disk in certain species (usually the hydroid 
medusz), there is a horizontal shelf, called the velum, or veil, be- 
cause it sometimes falls like a veil. 
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