DEVELOPMENT OF JELLY-FISHES. 67 
shorter and thicker than in the males. The eggs pass out 
of the mouth into the water along the channeled arms, and 
in October the ciliated gastrula becomes pear-shaped and 
attaches itself to rocks, dead shells, or sea-weeds, and then 
assumes a Hydra form with often twenty-four very long 
tentacles. This stage was originally described as a distinct 
animal under the name of Scyphistoma. In this Scyphis- 
toma stage (Fig. 45) it remains about eighteen months. 
Toward the end of this period the body increases in size 
and divides into aseries of cup-shaped disks. These saucer- 
like disks are scalloped on the upturned edge, tentacles bud 
Fig. 48.—Aurelia flavidula.—After Agassiz. 
out, and the animal assumes the Strobila stage (Fig. 46). 
Finally, the disks separate, the upper one becomes detached 
and with the other disks swims away in the Hphyra form 
(Fig. 47), when about a fifth of an inch in diameter, and 
toward the middle or end of summer becomes an adult 
Aurelia (Fig. 48). 
Though the Aurelia has lasso-cells it is not poisonous to 
bathers. Not so, however, with the gigantic Cyanea arctica, 
whose long tentacles are poisonuus ; fishermen as well as 
bathers being often annoyed by them. This giant jelly-fish 
sometimes attains a diameter of from three to five feet across 
