SAND DUNES AND SALT MAESHES 



—but not denizens of it, as the heading of this 

 chapter would imply— the once free-swim- 

 ming jellyfishes. They are sadly bedraggled 

 by the waves, and entirely lack the graceful 

 form and throbbing rhythmical movements 

 which so excite our wonder when the animals 

 are at home on the surface of the sea. The 

 commonest of these is aurelia, with its trans- 

 parent bluish-white disk eight or ten inches 

 in diameter, and its group of four sacs in the 

 middle, conspicuously straw colored or yellow 

 in the females and pinkish in males. In the 

 early part of the summer these jellyfishes 

 swim strongly, and generally avoid the beach, 

 but towards the end of the summer they be- 

 come old and feeble, and are more often cast 

 ashore. At this time the strange looking 

 young, which are retained in the folds under 

 the disks, are set free and attach themselves 

 to rocks or seaweed, where they develop into 

 little saucers piled one above the other, to be 

 released and become veritable jellyfish the 

 next spring. 



Less frequently the large red arctic jelly- 

 fish is thrown up on the beach, looking like 

 a great disorganized mass of coffee jelly. In 

 its prime at sea this is a wonderful animal, 



262 



