PKEFACE. 



only been described from preserved specimens. A Prodromus, or 

 preliminary issue, in the form of Decades, or numbers of ten plates, 

 each with its complete descriptive letterpress, will be published, of 

 such illustrations as are ready, without systematic order or waiting 

 for the completion of any one branch. The many good observers 

 in the country will thus have the means of accurately identifying 

 various natural objects, their observations on which, if recorded and 

 sent to the National Museum, where the originals of all the figures 

 and descriptions are preserved, will be duly acknowledged, and 

 will materially help in the preparation of the final systematic volume 

 to be published for each class when it approaches completion. 



In the first plate (91) of this tenth Decade there is the first 

 coloured representation of that most curious and rare Marsupial, 

 the Gijmnohelideus Leadbeateri ; which, mth the form, feet, and 

 dentition of the beautiful Marsupial so-called Flying Squirrels of 

 Australia, constituting the genus Belideus^ is entii'ely destitute 

 of the lateral expansion of skin forming the parachute which 

 enables the Belidei, like the true Flying SquuTels of other 

 countries, to almost fly, in their sustained jumps from one tree to 

 another. 



The second and third plates show the natural colours for the 

 first tune of a River Tortoise, the Chelodina longicollis^ which 

 abounds in many of the rivers of Gi23psland, and more rarely in 

 the Murray, where the Chelymys Macquaria (figured in our 

 plates 82 and 83) is the common Tortoise — a species not known 

 in the rivers flowing south into the sea. 



The six following plates illustrate a splendid series of 

 Victorian species of Retepora^ contributed by Dr. MacGillivray 

 to the National Museum and this work. 



The last plate gives full details of the fine Sea-Urchin, the 

 Goniocidaris tuharia., with its extraordinary variety of spines j all 



[4] 



