410 Dr. R. von Lendenfeld on 



I have found occasion to draw attention to the fact that 

 Crambessa mosaica in Sydney was brown, whilst in Melbourne 

 the same species always appeared deep blue. The brown 

 colour is not always of the same depth and of similar hue all 

 over the surface of the Medusa, but varies from the colour of 

 white bread to that of coffee. The cause of this colour is to 

 be found in small yellow cells, which appear in more or less 

 dense clusters all over the surface. These cells are parasitic 

 Algas known as Zooxantliella. It does not appear unlikely 

 that they may be the young stages of ordinary Laminarians. 



Such Zooxanthelhe. are very common in jelly-fish, sponges, 

 &c., all over the world. Also in Port Phillip I obtained 

 numerous Actiniae which were infested by them. The Cram- 

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

 a Zooxantliella^ and so retains its original blue colour. 



In the harbour of Sydney, on the other hand, Zooxanthellce 

 which appear identical with those in Melbourne are found in 

 great masses in all Cramhessce. 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 quite 

 brown. 



With the trawl we sometimes brought up Cramhessce from 

 depths of 10 or 20 metres which did not show the brown 

 colour very distinctly, and it appeared that only a few masses 

 of Zooxanthellce 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 differ- 

 ence between the Sydney and Melbourne species as sufficient 

 to make two varieties of them. 



In the cold water of Port Phillip it apj^ears not to be 

 advantageous for the Medusee or the Alg03 to live symbiotic, 

 whilst tills does appear to be the case in the warm water of 

 Port Jackson. The Melbourne variety, which I name Cram- 

 bessa mosaica conservativa^ is blue, and has apparently retained 

 the habits of its ancestors. The Sydney variety, which I 

 shall name Crambessa mosaica symbiotica^ has given up this 

 mode of life, and has taken to live together with a Zooxan- 

 thella. The diflerence between the two is evidently the same 

 as that between fungi and lichens. Should the variety 

 symbiotica adapt itself, in the ordinary course of natural 

 selection, so wholly to this symbiotism as not to be able to 

 live without the Zooxantliella^ a new species will have been 

 formed, which may perhaps be the case already. 



Crambessa mosaica has been described by several authors. 

 All the specimens were collected near Sydney, and the species 



