244 THE GREAT BARRIER REEF. 



glonicrata. Apart from this form, which, as hereafter shown, embraces a number of varieties, 

 there are several specific types of oysters indigenous to Queensland waters, which, while 

 neither at present so easily accessible, nor possessing other minor disqualifications, are whole- 

 some eatingj they will doubtless in future years be utilised more or less extensivel}' for both 

 home consumption and the export trade. In the former connection, as a matter of fact, 

 certain of these supplementary^ species have already begun to command a market. 



Although both the natural and the artificially-culti\-ated banks and beds of the leading com- 

 mercial oyster are mainly associated with the extensive areas of Moreton and Wide Bay, in the 

 southern districts of the colony, one and all of the specific forms hereafter enumerated, are 

 denizens of the tropical waters of the eastern coast-line, and consequently fall legitimately within 

 the category of the " Products " of the Great Barrier district. Ostrea gloiiierata occurs, in fact, in 

 a cultivable form in close proximity to the central and northern townships of Rockhampton, 

 Cairns, and Cooktown; while the headquarters of the majority of the other species referred to are 

 the coral, or rocky, islets, of the Great Barrier system. 



The largest edible form of oyster found in Queensland waters is distinguished bj' the title of 

 the cockscomb 03'Ster, Ostira cristi-galli, so called from the regular zigzag undulations of the outer 

 edge of its interlocking valves having some resemblance to a cockscomb. An illustration of 

 this species will be found at Chromo plate XIV., Fig. 5. A pair of the ponderous shells of this 

 oyster not unfrequently weigh as much as from 5 to 7 lb., and have a diameter of from eight to 

 twelve inches. The species is an essentially salt-water form, and limited in its distribution to the 

 tropics. It grows plentifully among the coral-reefs of Torres Strait and the Great Barrier sj'stem, 

 in either an entirely submerged condition, or, where exposed to atmospheric influences, at ordinary 

 spring tides. Under these last-named conditions, it has been observed by the author in especial 

 abundance on the fringing coral-reefs surrounding what are known as M and N Islands, belonging 

 to the Northumberland group, eastward of Mackay. This oyster is also to be seen in some quantities 

 III situ, but no longer alive, on the dead, and apparently raised, coral-reef on the west side of Mag- 

 netic Island, facing Townsville. As an edible variety, the coxcomb oyster is somewhat large and 

 coarse, and is consequently most appreciated in a cooked condition. A smaller species of cockscomb 

 oyster is not unfrequently obtained from deeper water in Torres Strait, attached to the branches 

 of the black coral, Antipatlics, and other zoophytes. It is remarkable for its production of finger- 

 like projections from the back of the attached valve. With the aid of these projections it retains a 

 secure grasp on its chosen fulcrum, though at the same time its hold ma^' be so loose that the 

 shell may be slipped to and fro on its supporting base. This variety of oyster would appear to be 

 identical with the Ostrea folium of Linnaeus, originally recorded from the Indian Ocean. 



The second largest species of edible Queensland oyster is also an essentially marine type, 

 and limited in its distribution to the tropical districts. It varies considerably in form, and may 

 be either simply ovate with a broader distal margin, or boat-shaped with pointed ends, as shown 



