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CHAPTER XVII. 



ACALEPH^E OR JELLY-FISHES. 



Medusae and Khizostomata. Their Internal Structure. Their Mode of Progression. 

 Alternation of Generations. Ciliograde Jelly-fishes. Their wonderful Fish- 

 ing Apparatus. Diphyes. Agalma. Physalus. Velella. Importance of the 

 Acalephse in the Economy of the Ocean. 



NOT less admirable than the coral- myriads which pave the 

 bottom of the ocean with petrified gardens and animated flower- 

 beds, are the soft crystalline hosts of the AcalephaB or Jelly- 

 fishes, whose incredible numbers excite the astonishment of the 

 mariner when for days together he steers through their in- 

 numerable shoals. The variety and singularity of their forms, 

 the brilliancy of colour which makes many of them true gems 

 of the ocean, their remarkable structure and wonderful trans- 

 formations, all contribute to delight the spectator, and to raise 

 the interest of the naturalist. 



When walking on the beach we chance to see a Jelly-fish 

 abandoned by the retreating flood, we can hardly imagine 

 how this disgusting gelatinous mass can ever have had claims 

 to beauty ; but this collapsed and formless wreck was elegant 

 and handsome while it moved along in its own native ele- 

 ment, and its organisation shows no less the wisdom of the 

 Creator than the more complex though not more perfect struc- 

 ture of the higher stages of animal existence. 



A soft gelatinous transparent or translucent body, without 

 a calcareous skeleton or intestinal duct, and whose parts, divi- 

 sible by four, are mostly ranged in a radiate manner round a 

 centre, is the common character of all the Acalepha? ; but their 

 chief divisions or groups bell-shaped, ribbed, or tubular show 

 such remarkable differences in their external forms and inter- 

 nal structures that it is hardly possible to comprise them in one 



