JELLY FISHES. 



53 



b 



Settling on a rock or shell, they develop into Hydra tuba, with 

 long tentacles, as at a a. Then comes the saucer-like stage, 

 as at b ; finally the free-swimming segment, c, which ultimately 

 becomes the huge creature of our next illustration, which is so 

 plentiful in our seas during summer and early autumn. 



Every person that has any 

 acquaintance with Jelly-fishes at 

 all knows this species well by 

 sight. It is probable that many 

 of those who think they know it 

 would be somewhat puzzled if 

 asked to point out the creature's 

 mouth and to give a rough out- 

 line of its organization. It may 

 be described roughly as umbrella- 

 shaped. There is an arched disk, 

 from the centre of which, on the 

 concave or lower surface there 

 depends a thick cylindrical body, 

 the manubrium or handle, some- 

 times erroneously termed the^/x- 

 pite, which finally terminates in 

 four lobes assuming the form of trailing ribbons. In the centre 

 of these lobes is the creature's mouth, and the stomach is 

 continued from the mouth up the middle of the manubrium. 

 Here digestion takes place, and the nutriment thus obtained 

 is carried up to the centre of the umbrella, and thence dis- 

 tributed to all parts by means of nutrient tubes which may 

 be seen running straight from the centre to the circumference. 

 Looked at from above, the Aurelia will be seen to have its 

 disk symmetrically marked off into eight portions by these 

 nutrient tubes, each of which reaches the edge where there is 

 a little notch, and then continues round the margin. Now at 

 the notch there is a ganglion, or nerve centre, a kind of local 

 brain, for the Jelly-fish is very low in the scale of nervous 



LAKV^i OF AURELIA. 



