338 ZOOLOGY. 



HYDEOZOA OE ACALEPHS. 



WATER IN MEDUSA. 



Some time ago it was stated by Professor Mobius that in a specimen 

 of Aurelia aurita, from the Bay of Kiel, it had been ascertained that 

 there was 99.82 per cent, of water, and consequently the solid matter 

 could only have formed a small fraction of 1 per cent. This statement 

 was so remarkable that, before acceptance, it required verification, and 

 Dr. Krukeuberg has recently examined specimens of the class, with the 

 object of verifying or disproving the allegation.* 



Specimens of Aurelia found at Triest were examined, and it was found 

 that the water formed only from 95.84 to 95.79 per cent, of the total 

 the solid existing in the ratio of from 4.21 to 4.66 per cent. Chrysaom 

 hyoscella afforded 95.75 per cent, to 96.3 per cent, of water, and there 

 was from 3.7 to 4.25 of solid substances. A large specimen ofRhhostoma 

 Guvieri was found to contain 95.392 per cent, of water, and consequently 

 nearly 5 of solid matter, of which there were 1.608 per cent, of organic 

 and 3 per cent, of inorganic substances. It was concluded that proba- 

 bly the MedussB generally exhibit a close approximation to these results, 

 and that in none is there so small a percentage of solid matter to be 

 found as in the case instanced by Mobius. 



EXTRA-MARINE MEDUSA. 



There is, perhaps, no type of animals that has been generally regarded 

 as being so eminently characteristic of the open sea as the Medusa?. While 

 representatives of the class exhibiting the hydriform condition have of 

 course been long well known as inhabitants of fresh waters, until recently 

 none of the medusiform groups have been specially noticed as havin- 

 been found elsewhere than in the sea. It has been said of them that 

 they dread nothing more than fresh water, and that such water is really 

 poison to them; that even brackish water kills them immediately; and, 

 further, that they need a water rich in oxygen and constantly renewed 

 by movements of the waves and currents. " The Medusw, in fact, have 

 almost an equal dread of fresh water, of stagnant sea-water, and of a 

 slightly too high temperature." Several cases, however, have been 

 recorded within the last two years which must materially modify the 

 accepted beliefs with regard to their habitat. 



PRESH-WATER MEDUSA. 



Mr. Agassiz has shown f that the idea respecting the exclusive con- 

 finement of Medusai to perfectly salt and clean sea water is exaggerated 

 He records that in an estuary back of Boston harbor, at West^Boston 



* C. F. W. Krukenberg. On the distribution of the water of the organic, and inor- 

 ganic coraponnds in the body of Invertebrates. Ve^-gl.-Fhysiol. Stud. KiisL Adria. I, 

 part 11, pp. 78-106. {J. R. M. S.) ' 



t Agassiz (Alexander). As quoted in Journ. R. Micr. Soc, vol. iii, p. 968. 



