18 AYDROIDS, ETC. 
These jellies are disk-shaped, the tentacles in Cya- 
nea hanging in eight distinct bunches from the margin, 
and armed with darts or lasso-cells, that form terrible 
Oi 
TG 
fl 
Ny 
WT iva 
; i 
DOS shay 
Mec.Qatrrcay yy” 
se Wi 
Fic. 16.—Adult Aurelia, showing the water-vascular canals, 
weapons of defense. 
eight protected eyes. 
» 
Around the fringed margin are 
The mouth-opening is square, 
leading into a large stomach, from which radiate four 
branching tubes (Fig. 16) called water-vascular canals. 
Fic. 17.—Development of Au- 
relia, 1. Early stage. 2. 
Jelly-fish ready to break off. 
They form a network at the 
edge, and connect with a tube 
that encircles the margin of 
the disk. Through these 
branches digested food and 
water circulates, or finds its 
way over the body. A some- 
what similar arrangement is 
found in all jelly-fishes. In 
swimming, the disk contracts 
and expands in regular time, 
averaging twelve or fifteen times 
a minute. 
