PRESIDENTIAL ADDRESS. 



59 



M*A 



A W. 



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Fig. 22. The Sea Cabbage TJlva lactuca, 

 natural size, from near Mrs. Macquarie's 

 Chair. 



locally it occurs at 

 intervals from ex- 

 posed positions, such 

 as the outer North 

 Head to sheltered 

 water at Mrs. Mac- 

 quarie's Chair. 



At the lowest inter- 

 tidal horizon com- 

 mence the brown 

 sea-weeds, Eklonia, 

 Sargassum and Cys- 

 tophora, which cor- 

 respond to the Laminarian 

 zone of Europe. The water 

 here is too warm for the giant 

 kelp, so conspicuous and 

 abundant in Tasmania and 

 south New Zealand. Its 

 place is taken by a dwarf 

 kelp, Eklonia radiata var. 

 exasperata (fig. 23). For the 

 identification of this andother 

 algae I am indebted to the 

 kindnessof Mr. A. H.S.Lucas. 

 The Eklonia is secured to the 

 rocks by spreading digitate 

 rootlets arising from a long 

 rope-like stalk. This stem 

 flattens above expanding to a 

 blade whence spring large 

 thin lobed leaves, whose sur- 

 face is closely wrinkled, and 



Fig. 23. Eklonia radiata v&r.exasper- _ . . ... 



*, , o , , , , , , whose margin is beset with 



aia, the dwari kelp, a plant about a ° 



yard high, characteristic of a zone thorn-Shaped processes. This 



below low tide level. 



