87 



by me for thi:^ purpose, both at Tliursday Isjlaud and various 

 stations connected with the Cireat Barrier System as far south as 

 Bowen. A reference to these photographs obtained (exhibited) 

 will convey a very tolerable idea of the aspect of various descrip- 

 tions of coral reefs and coral growth, as exposed to view at 

 extreme low spring tides. The element of colour, however, is the 

 one thing wanting to render the imaiierv complete. As will be 

 observed, separate varieties of corals predominate in the different 

 views. One of these represents an almost unbroken field or 

 forest, many acres in extent, of a branching Madrepora, coloured 

 brown with white or ])ale yellow tips. In another, a coryinbese 

 form of the same genus — Madrepora — tinted a dull green with 

 yellow terminations, forms encrusting masses throughout the 

 landscape. Large massive Astreas, St/mphi/Ilias, and JMeandr/iias 

 enter most extensively into the composition of a third series, 

 while a fourth will be found to contain a commingling of species 

 too extensive for enumeration, and presenting, as seen in a state 

 of nature, a variety of form and colour challenging comparison 

 with that of the gayest flower bed. 



From a practical point of view, theaccjuisition of reliable data 

 concerning the rate of growth of coral reefs and of their compo- 

 nent corals is of considerable import. There is strong reason for 

 suspecting that a large portion of the reef-forming species in- 

 crease in dimensions at so appreciable a rate, that waters in the 

 coral seas surveyed and declared safe for navigation, twenty vears 

 ago or more, may now contain many hidden dangers arising from 

 the upward growth of isolated or accumulated coral masses. 

 The true nature of the submarine obstacle upon wliich the ill- 

 fated '" Quetta " came to an untimely end, has not yet beeji deter- 

 mined, though the probabilities are that it is a pinnacle of rock 

 capped with a continually upward growing coral mass, that has 

 within recent times been brought to within striking distance of the 

 keels of deeply laden vessels. That such phenomena are in course 

 of progress was moreover substantially proved by H.M.S. " Eam- 

 bler," during her recent survey in search of the Thales rock in 

 the direction of the Booby Lightship, to the north west of Thux'sday 



