president's address SECTION D. 331 



A consiJeralile proportion of our fauna is as yet unknown abroad. 

 Further research will, liowever, alter the proportion of endemic forms 

 l>oth by the discovery of Queensland forras beyond. our limits, and by 

 the recognition in our waters of species described from Japan, the 

 Philippines, and elsewhere. But the completed returns will follow the 

 direction indicated by incomplete data. We note the absence from 

 our beaches of several genera, such as Harpa, which otherwise range 

 over the whole Indo-Pacific area. Cyprcea mauritiana, i ne of the 

 commonest and widest-spread Indo-Pacific forms, is yet one of the 

 rarest Queensland shells, presumably a recsnt immigrant not yet 

 established. 



A glance at the physical evolution of the Coral Sea and east coast 

 of Queensland, may suggest a clue to the isolation and peculiarity of 

 our fauna. 



According to Neumayr (Denkschr. k. Akad. d. Wiss. Wien., Math., 

 Naturw. cl. L., Abth. I., Karte I.), a meridional crease in the earth's 

 ■crust produced in Jurassic times a gulf, which he called the Gulf of 

 Queensland, whose western shore transgressed tlie present east Aus- 

 tralian coast (Map A). Enlarging through geological cycles this gulf 

 grew into what we now know as the Tasman and the Coral Seas. 



South of the Louisiades, and east of Cape Melville, there occurred 

 a, sink whicli I venture to suggest originated in the Mesozoic, and in- 

 creased, during the whole Tertiaiy Period. It developed into the 

 Carpenter Deep of modem geographers. Our knowledge of this basin 

 is drawn from tlie observations of the " Challenger." In a traverse of 

 1,000 miles this great basin preserves an unbroken depth of more 

 than 2,000 fathoms. Temperature readings show it to be enclosed by 

 an unmapped rim, ^vhose lowest point is 1,300 fathoms. 



As the Mesozoic sink enlarged its periphery it became a dominant 

 factor in land configuration. First it broke through an older inner 

 earth fold of wdiich New Caledonia and the Louisiadeis are relics. 

 Then continuing its work to the eastwards, it subnierged a younger 

 ■outer continental ridge on which the Solomons stand. Westerly it 

 -erumpled up the former coast of North Queensland, and, by a furthest 

 westeni effort, broke open Torres Strait. 



While the Coral Sea was yet a prolongation of the oM Gulf, and 

 liad more or less the appearance sketclied in Map B, it offered a 

 refuge to old forms of life. The low latitude afforded a warm un- 

 changeable climate, and the surrounding continent secluded its 

 inhabitants from tlie incursion and competition of other tropical 

 fauna. When, however, continued subsidence to the east at last burst 

 through the Melanesian Plateau, a flood of active competitors must 

 liave swept in from tlie upen Pacific. This reached the Queensland 

 coast either l)y eiee|iing along the land round the Papuan Gulf or by 

 diiect, usually larval, transit across the Coral Sea. 



With the opening of Torres Strait, and the consequent outgoing 

 current, the Queensland fauna was spread along North Australia to 

 the Moluccas. By this route there escaped such forms as Trigonia, 

 Nautilus, Meleagrina maxinm, and M eg ahilr actus. Had such been 

 retained east of Torres Strait tney would have greatly Iieiglitencd the 

 jieculiarity of the Solanderian fauna. 



