926 LOCAL COLOUR-VARIETIES OF SCI1YPHOMEDUS.E, 



in all parts of the world. Also, m Port Phillip, I obtained 

 numerous Actinise, which were infested by them. The Cram- 

 bessa mosaica of Melbourne however, never shows a trace of a 

 Zooxanthella, and consequently retains its original blue colour. 

 In the harbour of Sydney on the other hand, Zooxanthella?, which 

 appear identical with those in Melbourne are found in great masses 

 in all Crambessse. In Sydney as well as in Melbourne I had 

 occasion to see many thousand specimens, and I found that the 

 Melbourne variety was always blue, but that the Sydney species 

 was not absolutely always cpiite brown. 



With the trawl we sometimes brought up Crambessse from depths 

 of 10 or 20 metres, which did not show the brown colour very 

 distinctly, and it appeared that only few heaps of Zooxanthelhe 

 could be detected with the magnifying glass. In every case some 

 yellow cells were present. 



I think that I might be justified in considering the difference 

 between the Sydney and Melbourne specimens as sufficient to 

 make two varieties of them. 



In the cold water of Port Phillip, it appears not to be advanta- 

 geous for the Medusa or the Algse to live symbiotic, whilst this does 

 appear to be the case in the warm water of Port Jackson. The 

 Melbourne variety which I name 



CRAMBESSA MOSAICA CONSERVATIVA 



is blue and has apparently retained the habits of its ancestors. 

 The Sydney variety which I shall name 



CRAMBESSA MOSAICA SYMBIOTICA, 



a i \en up this mode of life and has taken to live together with 

 a Zooxanthella. The difference between the two is evidently the 

 same as that between Fungi and Lichens. Should the variety Sym- 

 biotica adapt itself in the ordinary course of natural selection so 

 wholly to this Symbiotism so as not to be able to live without the 

 Zooxanthella a new species will have been formed, which may 

 perhaps be the case already. 



( 'ranibessa mosaica has been described by several authors (see 

 for reference my former paper the Scyphomedusai of the Southern 



