17 



Plate III. 



Pie;nre 1. — Lateral view of complete speoimen overlyins"; interior face of single-attached valve of 

 the black-bordered oyster, Osti-ea nigro-marginata, from Adolphus Island, Torres Straits. 



Figure 2. — Marginal view of complete example overlying interior face of attached valve of the 

 coxcomb oyster, Ostrea cristi-galli. From M Island, off Mackay. 



Figures 3 and 4. — Ventral and dorsal views of the " borer "-destroying whelk, Natica plumhea. 



Plate IV. 



Figure 1. — Boat-shaped example of black-bordered Oyster, Ostrea nigro-marginata. 



Figure 2. — Tubular oyster, Ostrea cor7iucopioe, showing at h the hinge, and at A' the path of 

 growth up which the hinge has gradually travelled with the increa.'-ing size of the shell. 



Figure 3. — Example of Ostrea cornucopias, showing the hinge path 7i^ more conspicuously. 



Figure 4. — Diagi-ammatic view of Ostrea cornucopicB, showing at a the points of attachment of the 

 adductor muscle, and by the clear space the dimensions of the internal cavity. 



Figure 5. — The saddle oyster, Ostrea sellaformis, internal view of a single valve. 



Figure 6. — Lateral aspect of the component valves of Ostrea sellaformis, showing their charac- 

 teristic indentation. 



Plate V. 



Figure 1. — A typical cultivated oyster bank, in Bribie Passage, Moreton Bay. From a photograph. 



Figure 2. — An undisturbed or virgin oyster reef, in the " Narrows," between Port Curtis and 

 Keppel Bay. A portion towards the centre of this reef having been undermined by the action of the 

 water, has partly fallen away, exhibiting the density of the oyster stratum. From a photograph. 



Plate VI. 



Figure 1. — A mangrove oyster bank in its initial condition, with oysters, Ostrea glomerata, attached 

 to the exposed roots and ventilating shoots or " cobbler's pegs " of the white mangrove, Aricennia 

 officinalis. Reproduced from a photograph from Moreton Island, Moreton Bay. 



Figure 2. — Mangrove oysters, Ostrea glomerata, attached to the elevated branching roots of the 

 Orange Mangrove, Ehizophora mucronata. Reproduced from a photograph taken in the estuary of the 

 Endeavour river, near Cooktown. 



Plate VII. 



Figure 1. — Typical rock oysters, Ostrea glomerata, growing on rocky boulders at the mouth of 

 Tullebudgera Creek, Burleigh Heads, near Southport. From a photograph. 



Figure 2. — A remarkably luxuriant mangrove oyster bank, consisting of solid masses of oysters, 

 that originated from individuals attached to the roots and " cobbler's pegs" of the White Mangrove, as 

 illustrated in Plate V., Fig. 1. From a photograph taken at Mangrove Island, Keppel Bay. 



Plate VIII. 



Oyster spat collectors constructed of " split palings" weighted with bricks and coated on the under 

 surface with cement. The top figure gives a lateral view of a simply cemented collector, and the four 

 lower figures the upturned surfaces of four collectors encrusted with oyster brood after remaining in the 

 water about four months. 



Plate IX. 



Illustrating the Embrology of the Queensland Commercial Oyster, Ostrea glomerata — Gould. 



Figures 1 and 2. — Unfertilised ova, with investing vitelline membrane and micropyle (a) magnified 

 about 500 diameters. 



Figure 3. — Milt or sperm cells. 



Figure 4. — Ovum with attached sperm cells immediately preceding amalgamation and fertilisation. 



Figure 5. — Fertilised ovum from first to second hour after fertilisation. 



Figuress 6 to 10. — Consecutive metamorphoses observable within the second and third hours after 

 fertilisation. 



Figures 11 to 13. — Changes progressing within the fourth to eighth hours after fertilisation, 

 terminating in the ejection of the polar cell, and the complete investment of the larger nutritive cells 

 or hypoblast, by the formative cells or epiblast. 



Figures 14 to 16. — Phases of the embryo known as the " Gastrula " type, observed between the 

 tenth and fifteenth hours of development. 



Figures 17 and 18. — Phases arrived at from within twenty-four to forty hours, and in which the 

 shells (sh.), mouth (?».), and vent, (t).), of the perfect oyster have made their appearance. 



Figures 19 and 20.— Lateral and doi-sal aspects of embryo three to four days old, and in which the 

 shells have grown to such dimensions that they entirely enclose the body when contracted ; magnified 

 about 200 diameters. 



Figure 21. — Earliest observed attached condition of the oyster embryos or "psat." Attained to 

 within the fourth or fifth day succeeding primary fertilisation of the ovum ; magnified about fifty 

 diameters. 



Price 3s. 8d.] 



By Authority : Jameb C. Beal, Q-OTcrnnieiit Printer, William street, Brisbane. 



