PHOTOTYPE PLATE NO. XXX. 49 



of coloured glass, which, it is anticipated, formed part of the captain's or officers' mess 

 equipment. 



Doubtless many another treasure lies hidden, and will probably' never be recovered from, 

 among the coral mazes of the Great Barrier Reef There is one sunken treasure, however, 

 of classic interest to all Australians, of which knowledge is certain, though the exact locale 

 cannot be fixed, that has again and again been the object of strenuous exertion to recover. 

 These are Captain Cook's guns, six in number, cast overboard from his exploring ship, the 

 Endeavour, when temporarily aground on a reef within sight of Cape Tribulation, a little to 

 the south of Cooktown, in the course of that earliest scientific survey of the Queensland and 

 East Australian coast. The position given by Captain Cook in the original description of his 

 travels (Vol. II., p. 135, 1821) as the scene of the disaster which so nearly wrecked his 

 vessel, is lat. 15" 45' S., and between six and seven leagues from the mainland. The ground 

 in the vicinity has been searched with the aid of divers, though so far without result, and it 

 is of course by no means improbable that the guns have long since been buried beneath an 

 impenetrable mass of growing coral. 



(B.)-JETSSM, STORM-STRflNDED CORIL-ROCKS. 



"Jetsam," the title most appropriately associated with the lower of the illustrations of Plate 

 XXX., is represented by a reef-scene in the Capricorn Islands group, depicting huge masses 

 of the consolidated coral-rock torn off its outer edge and hurled far up on the face of the level 

 platform reef Phenomena of this description are abundantly illustrated throughout the length 

 and breadth of the Barrier, and are mostly associated with the cyclonic storms that, during the 

 prevalence of the north-west monsoon, occasionally sweep the reefs with irresistible force, 

 though, fortunately, over limited areas. The larger rock-masses stranded on this reef-view are, 

 respectively, over a ton in weight, and consist exclusively of a conglomerate of coral fragments 

 varying from minutely comminuted particles, which constitute the main bulk of the mass, to 

 almost entire, though much eroded, coralla, inches or feet in diameter. The much-weathered, 

 uneven surfaces of these stranded coral-rocks offer a secure, permanent anchorage, or a tempo- 

 rary lodgment to a considerable host of molluscan and other littoral organisms. Barnacles, 

 multivalve Chitons, and the coral-rock oyster, Ostrea monlax, are distributed more particularly 

 over the upper surfaces of these rock-masses, while their ground storey, or excavated under- 

 surface, usually shelters a number of Holothurida; or Beche-de-mer, Holothuria atra and //. coluber, 

 which, during the rising of the tide, extend themselves on all sides in search of food. 



The rock-masses in this reef-view are entirely covered at high water. It frequently 

 happens, however, more especially on the outer or weather edge of the reef that the 

 detached storm-stranded blocks are of such dimensions that their crowns are elevated several 

 feet above high-water mark. Under these conditions their upper surfaces become perfectly 



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