OYSTERS AND OYSTER EISHERIES OE QUEENSLAND. 253 



the most important. These "bank oysters" may be attached to stones, or dead oyster-shells 

 known as cultch, or, as still more frequently happens, to the living shells of a peculiar species of 

 whelk, Potaiiudes cbcniniis, Brug., whose name, with the aborigines of Moreton Bay, is that of 

 " Toondah." This whelk, which grows to a length of three or four inches, is essentially 

 herbivorous, feeding on the Confervae, lower algae, and other vegetable organisms that abound 

 on the mud-flats so favourable to the growth of the oyster. The free-swimming oyster embryos 

 or " spat " become attached in large numbers to the exposed dorsal surfaces of the whelk's-shell, 

 and are carried about with it among the most lu.xuriant pasture grounds. Within a few months' 

 time the oysters have increased to such a size and weight that the whelk is no longer able 

 to travel with its burden ; and where the ground is soft it sinks into the mud and perishes, 

 leaving the living crown of oysters by way of a monument, to mark the position of its inter- 

 ment. Of the number of oysters originally adhering to the whelk, some four or five, repre- 

 senting the surviving " fittest," usually grow to maturity and marketable size. Exami- 

 nation of some very fine examples of whelk-oyster-growth obtained from Deceptive Bay, 

 proved that the load of oysters carried by the living whelk frequently weighed as much or 

 more than half a pound, while the whelk itself barely weighed an ounce. A characteristic 

 illustration of a whelk oyster bank from the Moreton Bay district, is afforded by the photo- 

 graphic view reproduced on Plate XLI.a ; while a whelk, Potamides, with an attached crop 

 of young oysters is delineated in Fig. 9 of Chromo plate No. XIV. 



An illustration of another oyster-bank, representing one of the rich oyster-grounds of the 

 Bribie Passage, Moreton Bay, is given at Plate V., Fig. i. It is noteworthy that the banks in this 

 district are formed more exclusively of oysters attached to ironstone pebbles, lying upon a substra- 

 tum of gravel and tenacious mud. They enjoy a high reputation for their shape, size, and flavour. 

 Oyster-banks of a similar character exist in the most luxuriant natural conditions throughout 

 Moreton and Wide Bays, the northernmost point of their occurrence being Rodd Harbour and 

 " Seven-Mile Creek," a little south of Gladstone and Port Curtis. The oysters on these northern 

 beds grow under conditions — on whelks or on separate shell or stone bases — precisel}' parallel 

 with those of their southern congeners, but they do not, in that higher latitude, attain to so large 

 a size. The experiment of transporting these smaller northern oysters to southern banks is 

 now under trial, with every promise of a successful issue ; though the considerable interval 

 of, approximately, twelve months has apparently to elapse before the new growth commences 

 which is necessary to bring them up to marketable dimensions. 



Concerning bank oysters generally, it may be mentioned that this form of growth repre- 

 sents the most important one, from a commercial standpoint. Not only are the largest numbers 

 of oysters sent to market taken from the banks, but bank culture furnishes employment and 

 a livelihood to a very extensive section of the community. In this connection, it may be affirmed 

 that probably in no other country in the world is so healthy, congenial, and non-laborious a means 



