The Zoologist — October, 18G7. 957 



at several places along the coast, as at Pitt Water, Brisbane Water, Botany Bay, Port 

 Aiiken, Wogonga, Jervis Bay, Syilney Harbour and Panbula. The Western Port, 

 Port Albert and Port Phillip oysters in Victoria, and the Spring Bay oysters in Tas- 

 mania, are all of this species. The other kind of oyster, whether named rock, cluster, 

 drift, bank, whelk, channel, mangrove, half-tide, or bay oysters, are of one species, and 

 all have in common a very hard shell; they will live out of the water from three to six 

 weeks and improve. The beds or grounds are all situated in salt-water creeks ex- 

 tending inland, and communicating with rivers, or in estuaries, where there is a strong 

 tide-way. They are mostly attached to each other in bunches, the roots of which are 

 firmly fixed in the bed, some adhering to rocks, boulders, mangrove stumps, snags and 

 whelks, but are never found unattached : the oysters of this class will require a very 

 different system of protection to the former. The spawning season differs in each river; 

 in some, each bed has a different time; in many places the bank and deep-water 

 oysters differ as much as six months in their time of spawning. Some oysters have 

 been known to spawn only once in three years, while others again will spawn two or 

 three times in a year ; but in all cases they are very much influenced by the weather, 

 for, when any are ready to spawn, a cold, rainy south-east wind setting in will throw 

 them back for a month. The greater portion of the oyster-spawn or spat that escapes 

 destruction will be found attached to the large oysters, and when about two months old 

 has the appearance of a fish-scale, and has but one perfect shell, the other being only 

 partially developed, and cannot be removed from its place of attachment without 

 destroying it. For these reasons I consider that a general close season, or three or 

 four months in the year, would be all but useless, as no particular three or four months 

 in the year will cover the spawning season of half of the oysters, and it would be very 

 little protection to those it did cover, as directly after the close season the oysters may 

 be taken, and from it being impossible to separate the young oysters their destruction 

 will be inevitable when the old ones are removed. The proposed close time is also not 

 a general spawning season, but occurs when most of the oysters are in the finest 

 condition — the Camden Haven, Manning and George's River (deep-water oysters), 

 and the Port Stephen bank-oysters spawning in May. One cause of the deterioration 

 of certain oyster-beds is that, after the regular oyster-gatherers have discontinued 

 working, and left them to recover, settlers and others are continually dredging, thus 

 destroying the young oysters. Another great cause of destruction is the taking of 

 oysters and shells to burn into lime; the shell-dredgers on the Hunter, for example, 

 go to work on any part of the oyster-grounds, taking up oysters and shell indis- 

 criminately, thus not only destroying the oysters but the oyster-grounds as well, 

 removing the whole of the bed, which, in many instances, is six feet thick of solid 

 shell, leaving nothing to which the spat can attach itself; and thus thousands of 

 bushels of oysters arc destroyed, and the beds are gradually reduced in size. From 

 Broken Bay there are four or five vessels constantly employed in bringing live shell- 

 that is, young oysters— to Sydney for the lime-burners. They bring about 65,000 

 bushels annually, in addition to which about half that quantity is burnt in the river, 

 making a total of 97,500 bushels of young oysters destroyed every year, in that 

 place only ; and a similar destruction is taking place over nearly all the oyster-grounds. 

 Oyster-beds are often destroyed by freshes in the rivers, covering them with a deposit 

 of silt; and a shift in the channel of a river will sometimes be another cause of their 

 destruction by diverting their food. Oyster-beds are considerably improved by being 



