NOTES ON THE EMBRYOLOGY OF THE 

 AUSTRALIAN ROCK OYSTER 



((Jstrea (jh)mfnit(i ). 



By W. SAVILLE-KENT, F.L.S., F.Z.S., &c., 



Commissioner of Fisheries, Queensland. 



[Itead hefore the Jini/al S,,rieti/ of 'Jnon-^hnul, l',l>. 14t/i, I'SOO.] 



A CONSIDERABLE aiiiouut ot' uncertainty liaving hitherto prevailed 

 concerning the tlevelopmental phenomena of the Austrahan rock 

 oyster of commerce {(htjra (ilotiunitit), I have recently devoted 

 some attention to this subject, and propose to submit to you on 

 this occasion a brief sunnnary of the results of my investigation:?. 

 It is desirable that I should point out, in the first place, that 

 the researches that have been already conducted by European 

 and American naturalists, with relation to the connncrcial oysters 

 of the Northern hemisphere, have elicited the fact that the 

 fertilisation and development of the oyster brood or spat is 

 formulated on two essentially distinct plans. In the case of the 

 most familiar European type, Oxtir(( /■duli.s, represented by the 

 far-famed British native and the variety so extensively cultivated 

 on the coast of France, the propagation of the species is, as will 

 be familiar to many present, accompanied by a condition in 

 which the oyster is unfit for consumption, and is prohibited to 

 be sold. This is occasioned through the circumstance that the 

 parent oyster nurses or incubates its brood within the pallial or 

 mantle cavity, throughout the early stages of its development, 

 and does not liberate it until the shells of the young oysters are 



