November, 1912. 



KNOWLEDGE. 



429 



in 1909 the latter was taken over by a syndicate, the 

 Montebello Shell Syndicate, Ltd. The first season 

 in which work was carried on was 1904. A tidal 

 pond, an acre in extent, was made by closing a 

 natural bay with a wail and sluice. (See F'igures 

 458 and 459.) The pond could be emptied by 

 specially constructed syphons. Between two 

 hundred and three hundred shell were laid down 

 in this pond, as breeding stock, and thev 

 throve well. No young shell appeared in the pond. 



Catcliment of various kinds was provided. E.xamples 

 from the breeding stock were examined from time to 

 time, and the maturation of the gonads tested. 



Young oysters, of a kind, appeared. The first 

 were seen nineteen days after the breeding stock 

 were laid down ; a few were as much as one-eighth 

 of an inch in diameter. These and subsetjuent 

 deposits of young oysters all died oft". It is not 

 possible to say whether they were [jroduced b\' the 

 oysters in the pond, or w hether the\- were " bastard " 



Hy the courtesy 



Figure 459. A view of the Tidal Pond Dam. 



of T. //. Hay. 



Further experiments were made in 1909-10: but 

 with inconclusive results. 



.\ third and more elaborate experiment was made 

 in the season 1910-11. The particulars of this 

 experiment, given below, were supplied to me by 

 Mr. Haynes. Mr. Haynes had determined that in 

 these waters the spatting season is between October 

 and April. A breeding stock was provided con- 

 sisting of o\sters which had been acclimatised to 

 the waters before the pre\ious season. They were 

 ascertained to have maturing gonads in November, 

 1910. 



As a preliniinar\- to the experiment the pond was 

 emptied, and all fish ejected. Between three 

 hundred and four hundred breeding oysters were 

 introduced. The pond was closed, and the only 

 change of water occurred bv the falling of the level 

 some nine inches on the ebb owing to percolation 

 through the bottom, and bv the restoration of an 

 equal amount through the sluice on the flood-tide. 



shell, introduced in the water at flood tide. Mr. 

 Haynes thinks the\- were young M. maxima, pro- 

 duced b\- his breeding stock, and it appears from a 

 Report bv him (Mother-of-pearl Shell Culture, 

 Report to the Directors of the Montebello Shell 

 Syndicate, Ltd., London, 1912) that Mr. Dannevig, 

 the Commonwealth Fisheries Officer, was inclined to 

 share his view ; but I am unable to agree with him, 

 though not denying the possibility of his contention, 

 (^f course, without siiecimens it is useless to discuss 

 what species the\' were ; indeed, I know of no 

 character which will allow of the identity of a 

 species of Margaritifera being safely diagnosed, at so 

 small a size. There is not, however, satisfactory 

 proof that the breeding stock emitted spawn in the 

 pond, and there is reason to think that at the close 

 of the experiment they had not yet done so. And, 

 although enough is not known of the duration of the 

 free-swimming stage of this species to allow me to 

 sa\- w hether the spat found nineteen days after the 



