io6 THE GREAT BARRIER REEF. 



collected from the drift accumulations on North-West reef These subjects will receive atten- 

 tion under their respective headings. A few casts with the dredge and tangles, made oft' 

 the reef in a depth of about twenty fathoms, produced an abundance of corals, referable to 

 two single species onl}', of the genera Seriatopora and Pocillopora, together with a few speci- 

 mens of the Solitary coral, Hctcropsammia Michelini. 



Before leaving the Capricorn group of reefs and islets, it has been thought desirable to 

 include a further abstract from Mr. Jukes' narrative of H.M.S. Flys survey of this particular 

 area, in which are embodied many interesting data concerning the geological composition of 

 the reefs. As a geological specialist, he was in a position to speak ex cathedra upon this 

 subject. Two coral islets, One-Tree Island and Heron Island, the latter visible on the 

 horizon of the photographic view reproduced in Plate XXX., were the field of Mr. Jukes' 

 explorations. The diary of his experiences is as follows : — 



"Jan. II. — Landed on this (One-Tree) island, which exhibited the same general features as 

 Bunker's first island, with some modifications. The external ridge of loose coral fragments was 

 loftier and steeper, owing, I believe, to this island being rather more on the weather, or at least the 

 south side of the reef. Inside, the island sloped down every way towards the centre, forming a 

 shallow basin, in the middle of which was a small hole of salt-water at or near the level of the sea. 

 The inside slope was covered with low succulent plants with pink flowers (Mesembryanthemum) and 

 low trailing bushes. On this green carpet were multitudes of young terns that fluttered before us 

 like flocks of ducklings, with the old birds darting and screaming over our heads. In the single 

 tree (which was, in fact, a small clump of the common Pandanus of these seas with its roots 

 exposed above ground) was a large rude mass of old sticks, the nest of some bird of prey, probably 

 the osprey. To the northward and eastward of the island stretched the shoal lagoon, its bottom 

 of clean white sand, and dark patches of dead and living coral, bounded by the usual rim of snow- 

 white breakers. Just round the island, part of the body of the reef was now exposed at low water. 

 This was a flat surface of about a quarter of a mile in width, dotted here and there with pools and 

 holes of water. It consisted of a compact, tough, but rather soft and spongy rock, many loose 

 slabs of which, two or three inches thick, were lying about. It was rather fine-grained, and only 

 here and there exhibited any organic structure or remains. There were no signs of living coral, 

 except a few stunted specimens in some of the deeper holes of the reef, where also were some dead 

 masses still standing in the position cf growth. The whole was very different from any precon- 

 ceived notions of a coral reef, and I erroneously imagined it must be an exception to their general 

 character; it looked simply like a half-drowned mass of dirty brown sandstone, on which a few 

 stunted corals had taken root. 



"Jan. 12. — We were anchored a few miles farther to the N.W. in the centre of a group of 

 reefs and islarids, under one thickly wooded island that afterwards obtained the name of Heron 

 Island. In attempting to land at low water, we were compelled to quit the boat soon after getting 



