2 6o THE GREAT BARRIER REEF. 



shallow water, they fell to the ground as each tide receded, and the young oysters became a 

 ready prey to crabs and whelks. This type of collector has also the drawback of getting water- 

 logged, and sinking to the bottom by its own weight, after prolonged immersion, when the 

 attached brood runs the same risk of premature destruction by its natural enemies or by the 

 accumulation of sand or mud. 



As an improvement upon, and simplification of, this ridge-tile collector, the author subse- 

 quently made use of the rough form of board known throughout the Australian colonies as "split 

 paling." Such palings — four feet long, eight inches wide, and one inch thick — were readily procur- 

 able at the low price of from eight to ten shillings per thousand. With a brick or stone attached 

 by wire to each end, on the under side, the surface between the two bricks coated with cement, 

 and a loop of wire fixed to the upper surface to serve as a handle, whereby they could be either 

 easily carried, lifted from, or lowered to, the bottom of the water with the aid of a boat-hook, they 

 were found to constitute the most convenient and economic form of collector that could be desired. 

 The bricks or stones on the under surface served the double purpose of anchoring the collectors 

 securely to the bottom of the water, and they at the same time raised the cemented surface above 

 the reach of predatory crabs and whelks. In practical application, these paling collectors were found 

 to possess all the efficiency of the French tiles, with the advantage of a far greater economy in 

 cost. The tiles, with individually smaller superficial areas for the attachment of the spat, cost 

 in France about £2 per thousand, and could scarcely be produced in Australia for double that 

 price. In order to test the efficiency of the "split paling" collector in connection with the 

 Queensland oyster, Ostrea glomerata, a few samples were constructed and experimentally placed on 

 ground, at a spot where a few mangrove oysters already existed, near the mouth of Nerang 

 Creek at the southern end of Moreton Bay. These collectors were deposited in the month of 

 July, 1890, and within three to four months from that date they were literally encrusted 

 with oyster brood, having shells, which averaged one inch in diameter. Two months later, a 

 large portion of these oysters measured individually as much as two inches in their longest 

 diameter ; and, being loosely attached by the butt-end, they were ripe for detachment and distribu- 

 tion on the ordinary cultivation banks. As many as 2,000 young oysters were thus found attached 

 to a single collector, being the equivalent of what, in the ordinary course of development, 

 would, by the end of another eighteen months, represent a standard two bushel-bag of 

 marketable oysters. 



Although the general employment of artificially prepared spat collectors upon the Queensland 

 oyster banks, as here described, is not recommended, and would scarcely be profitable under 

 the existing abundant supplies, and the extensive natural spawning grounds, at the disposal 

 of the leading lessees of the oyster fisheries, there are undoubtedly circumstances, and conditions, 

 under which their introduction would prove of value. With the aid of these and kindred collectors, 



