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starfishes of all descriptions, but more especially the ordinary five-fingered varieties, Aateridse, are 

 universally held up for condemnation as representing the most insatiable foos of the oyster tribe. Whether 

 this wholesale condemnation is a just one there are some reasons for doubting. In many instances it has 

 been observed that the starfishes were merely acting as scavengers, and preying on dead or dying bivalves. 

 The direct experiment was carried out by myself some years since in one of the large English public 

 aquaria of keeping oysters and starfish, including the accredited most aggressive species, [Jrasler rubens, in 

 the same tank. These two pre-supposed antipathetic types were thus maintained side by side in perfect 

 health for many months without a single instance occurring of molestation of the oysters on the part of 

 the starfish ; these latter, however, fed freely on portions of the cut-up fish occasionally placed in the 

 tanks. How far this vindication of the starfish's character would hold good in association with the 

 common shore species of South Queensland has yet to be demonstrated, and in the interim it is desirable in the 

 interests of the oyster-grower to recommend the clearance of this intruder as far as possible from off his beds 

 or banks. In this connection a suggestion concerning the destruction of starfish may prove acceptable. 

 It is by no means an uncommon practice among oyster cultivators on bringing up starfish in the dredge, or 

 finding them on the banks, to rip them in pieces and cast them aside or into the water again under the 

 impression that their life is destroyed. As a matter of fact each of the five finger-like processes 

 separated from the starfishes' body is capable of growing into a fresh starfish, so that by the process of 

 dismemberment the further multiplication of the species is accomplished. To encompass the certain 

 destruction of these animals it is desirable that they should be carried to land and be deposited above the 

 reach of the tide. 



The different species of Sea Urchins, or Sea-Eggs, Echini, have been occasionally associated with 

 oyster-eating proclivities. Their habits, however, are essentially herbivorous, and the only injury they 

 might possibly, but very improbably, do to oysters is that of piercing the very young and fragile shells 

 with their spines in passing over them. 



Many varieties of fish prey more or less extensively, though not exclusively, on oysters. Among 

 these may be mentioned the family of the toad-fishes, TetraJons, porcupine fish, Biodons, leather-jackets, 

 Monacanfhi, and the several varieties of breams, Pagridce. The most destructive fishes ou the oyster 

 banks are, however, undoubtedly the Sting-rays or " Stingarees," as they are popularly denominated, 

 belonging to the shark tribe and referable to the genus Trygan. The common dark brown species, Trygon 

 pastinaea, is probably the greatest delinquent in this direction. It abounds on the low-lying banks 

 throughout the oyster-growing districts, and commits serious havoc among the young stock with the 

 assistance of its pavement-like crushing teeth. A more typical oyster-eating member of the shark tribe 

 that abounds in the southern colonies and is occasionally taken in Moreton Bay is the so-called Port 

 Jackson shark, Heterodontus Pliilippi. It is of a tawny brown colour with an abnormally large head and 

 projecting brow ridges, and has a strong sharp spine developed in front of each of the two dorsal fins. It 

 rarely exceeds a length of 5 feet, but is provided with powerful crushing jaws, of greater strength 

 even than those of the Eays, and with which it easily breaks up the largest oyster shells. On 

 certain of the Tasmanian oyster reserves and private beds it wrought such havoc that the oysters were only 

 saved from entire destruction by fencing them round with wire netting. With reference to its oyster- 

 eating proclivities, the species is known in Tasmanian waters by the name of the "oyster crusher," while in 

 some parts of Victoria it is called the " pig-fish." By way of illustrating the peculiar hardness of its 

 palate it may be mentioned that in the neighbourhood of Port Jackson, New South Wales, it feeds very 

 extensively on the spine-covered Sea Urchins, Echini, its teeth being frequently stained a bright violet 

 hue through its predilection for this diet. 



A species of boring sponge, Hymeniacidon ceJata, has here, as in European waters, to be included 

 among the enemies of the oyster. Its attacks are, however, confined almost exclusively to old shells in 

 deep water, and which it honeycombs in every direction. The parasite is soon got rid of by the exposure 

 of the affected oysters to light and sunshine on the banks. 



Several species of birds, including notably the so-called oyster-catcher, Sematopus longirostris, and 

 the numerous members of the crane tribe that frequent the oyster banks at ebb-tide, prey to some extent 

 on the young oyster brood. Next to the borer, however, the greatest amount of injury to the oyster 

 cultivator's growing crops is probably committed by the innumerable species of crabs that infest the beds 

 and banks. 



A destructive agency that has caused great losses to the oyster-growers of New South Wales, and 

 of which there was some suspicion of its having made its appearance among the oysters in Wide Bay, is 

 what has been styled the " Worm Disease." This disease is characterised by the presence within the oyster 

 shells of patches of mud, which are more or less completely covered in by a a shelly or membranous redeposit. 

 One or more small worms, Leucodore ciliata, are almost invariably found enclosed within these mud- 

 cavities, and from which, through a tubular channel, they maintain a communication with the outer water. 

 This worm is usually credited with being the primary origin of the so-called disease, but on the 

 strength of a slight passing acquaintance made with it in New South Wales, and all the facts relating to 

 it that have been published, I am inclined to believe that the organism is only an accompaniment, and not the 

 cause of the disease. Mr. Whitelegge, of the Sydney Museum, who has approached the subject from the 

 standpoint of the worm being the originator of the disease, has made the following remarks, after 

 making investigations concerning its occurrence at the Hawkesbury Biver : — "The principal home of the 

 worm appears to be on the mud-flats about low water-mark. The oyster from this region, the Hawkesbury, 

 were invariably infected with the worm, particularly those which lay loose on the surface or were partially 

 buried in the mud. Those oysters which were fixed to some solid substance, and elevated ever so little 

 above the surface of the mud, were comparatively free from the pest." The foregoing testimony goes 

 far to show that this so-called worm disease is essentially a " dirt disease." It is only in a muddy environ- 

 ment, unsuitable for the healthy growth of the oyster, that it spreads, and that it is the mud, and not the 

 oyster ^er se, that attracts the worm, is demonstrated by the fact attested — that the oysters elevated 

 but a few inches above the muddy stratum are relatively free from the affection. 



The inference that I am inclined to arrive at concerning the occurrence and manifestations of this 

 disease, is that the oyster through the foulness of its surroundings absorbs within its shell cavity, by 

 the ciliary action of its gills, a greater amount of mud than it can get rid of, and that the worm in its 

 free-swimming embryonic state being drawn within this cavity by the same cilliary currents of the oyster, 

 settles down with alacrity within so congenial a mud-lined cradle. The worm, Leucodore ciliata, under 



discussion, 



