(5 



HERON ISLAND. 



was not till, a piece of the rock was broken open and 

 its component parts minutely examined, that its 

 purely calcareous nature and organic origin became 

 evident. Under the loose slabs we procured a few 

 cowries and other shells and some crabs, but altoge- 

 ther I confess ] was much disappointed with the 

 first view of a coral reef, both as to its beauty and 

 richness in animal life. The most beautiful things 

 were the hippopus and tridacna (chama gigas of 

 old voyagers), that were every where lying about 

 half buried in the rock ; when their shells were open, 

 and the mantle of the animal exposed, they were 

 seen to be of rich velvety blues or greens spotted 

 with black, or light brown spotted with yellow. 



Jan, 12. — We were anchored a few miles 

 farther to the N.W. in the centre of a group 

 of reefs and islands, under one thickly wooded island 

 that afterwards obtained the name of Heron Island. 

 In attempting to land at low water, we were com- 

 pelled to quit the boat soon after getting on the 

 edge of the reef, and wade ashore a distance of a 

 third of a mile. The bottom was very irregularly, 

 but pretty equally divided between white sand and 

 blocks of dead and living corals, principally the 

 former. On many of the rough blocks of coral 

 there was scarcely a few inches of water, and many 

 large masses, particularly along the outer edge of 

 the reef, were high and dry. All the sandy spots, 

 however, were about three to four feet deep, and as 

 neither the sandy spots nor the coral masses were 



