BY II. VOX LENDEXFELD, PH.D. 431 



The Fauna of Bass' Straits is . very different from that of the 

 warmer streams passing the east coast of Australia. At the 

 point, Jarvis Bay, where the warm current leaves the coast lies 

 the boundary between the Fauna of the cold Polar and the 

 warmer equatorial currents. The fish and shellfish at the north 

 Jarvis Bay are mostly different from those to the south of it ; but 

 in the Rhizostoma a movement has taken place which must 

 certainly be considered as the effect of the local current coming 

 from the east and flowing through Bass' Straits. The connection 

 through Bass' Straits of Port Phillip (Melbourne), and Glenelg 

 (Adelaide) is formed by the Polar current which here bends 

 towards the west and flows along the coast. 



Lastly the northern district is entirely disconnected from the 

 others, as a current coming from the Tropic Zone in the Pacific 

 Ocean flows through it. Strong local currents are of course met 

 with among the numerous islands, and these currents are the 

 cause of the wider distribution of the northern Medusa, The 

 current coming from south-east which flows along the coast of De 

 Witts' Land prevents any extension of the Medusae of this district 

 towards the south-west. None of these currents are violent, and 

 it may be taken for granted that living Medusae may be carried 

 downwards, but never extend upwards in these currents ; and 

 further that Medusae which are well known to be very sensitive 

 to any change in their surroundings are not likely to fight the 

 battle of existence with success if they leave that kind of sea- 

 water to which they are accustomed in which they live. 



Numerous Medusae, and especially the large Rhizostoma, swim 

 far up into sheltered bays and the mouths of rivers to deposit 

 their young, and are therefore confined by the formation of the 

 coast, as well as by the currents, to certain limits. 



Should any kind of Medusa get to a place where iis scypho- 

 storuae can flourish, for instance, in a sheltered harbour, and 

 should the circumstances of its new abode enable it to live, then 

 this harbour will remain a lasting dwelling place of such a 

 Medusa, 



