244 A, Agassiz — Great Barrier I^eef of Australia. 



of the islands off the shore are constantly scoured bj rain ; 

 thns silt is carried over the whole of the bottom of the inner 

 waters of the Great Barrier Reef. The shallower water of the 

 main inner channel, in depths of ten fathoms or less, is far from 

 clear ; it is only in the deeper channels of the inner reef flats, 

 in eighteen or more fathoms in depth, that the water becomes 

 clear. But even in those channels, and in the inner channels close 

 to the outer edges of the reef, the bottom is not composed of 

 coral sand silt, but is covered with blue mud derived from the 

 adjacent continental or island shores and flats. 



I hope soon to publish a more detailed account of our obser- 

 vations. 



I have to thank the State Department at Washington, the 

 Foreign office in London, and the Government of Queensland 

 for the interest they took in this expedition and for the facili- 

 ties for work offered me in consequence from every direction. 



