BY W. SAVILLE-KEXT, F.L.S., F.Z.S., ETC. 35 



inL' upon the discovery of Dr. Brooks in connection with the 

 American oyster, it was demonstrated by M. Bouchon-Brandeley, 

 in the year 1882, that the small Portuguese oyster, Ostrea 

 awjiihitu, exhibited developmental phenomena which coincided 

 essentially with those of the American species, the ova being 

 similarly discharged into the water, where they are fertilised 

 and developed independently of the parent. The artificial 

 fertilisation of the ova of this species, and the investigation of 

 the more impoitant embryological phases of this Portuguese 

 type, were also successfully carried out by the authority cited. 



The oysters of Australia, like those of the Northern hemi- 

 sphere, exhibit two distinct plans of propagation. The com- 

 mercial form indigenous to Tasmania and Victoria, but now so 

 reduced in numbers by exhaustive fishing as to be scarcely known 

 in the market, cannot be distinguished from the Ostrea edulis of 

 European waters, and is usually associated b}' naturalists with 

 the same specific title, but is sometimes denominated the variety 

 Ani/risi of the same type. The reproductive phenomena of this 

 oyster have been personally investigated by me, and were found 

 to coincide precisely with those of its European congener, the 

 embryos, in like manner, being fertilised and developed within 

 the mantle or pallial cavities of the parent. Similar phenomena 

 have also been found by me to obtain, in association with the 

 closely allied New Zealand mud oyster, and which is also 

 apparently a local variety only of the same species. 



The most important commercial oyster of Austraha is 

 undoubtedly the familiar rock oyster, (htre/i (jlomeratn, of which 

 Queensland enjoys the enN-iable position of producing the largest 

 supplies, Moreton Bay and Wide Bay alone growing sufficient 

 quantities not only for home consumption but also for exporta- 

 tion to the neighbouring colonies. The method of propagation 

 of this oyster to which I have paid some attention within the 

 past few weeks, is, I find, in all respects identical with that of 

 the American commercial species, Ostnui viraincana. The fer- 

 tilisation of the ova is brought about by their coming in contact 

 with the milt or sperm cells in the open water, the young embryos 

 being thus cast adrift and thrown upon their own resources from 

 the earliest period of their existence. The artificial propagation 

 of this species by the abstraction of the matured sexual elements, 

 the ova and spermatozoa, and their admixture m a little sea water. 



