299 



NOTE ON THE OCCURRENCE OF DIATOMS, RADIO- 

 LARIA AND INFUSORIA IN THE ROLLING 

 DOWNS FORMATION (LOWER CRETACEOUS), 

 QUEENSLAND. 



By W. S. Dun, W. H. Rands, F.G.S., and Professor 

 David, B.A., F.G.S., F.R.S. 



(Plates xvii.-xix.) 



i. — Introductory. 



This note is intended to be preliminary to a fuller description 

 which we hope to furnish later when a larger supply of the 

 material is available. 



Some years ago, by the courtesy of Mr. R. L. Jack, the late 

 Govt. Geologist of Queensland, one of the authors was allowed to 

 take a chip of limestone from a specimen in the Geol. Survey 

 Museum, Brisbane, with a view to examine it for Radiolaria. 

 The specimen came from the Maranoa River, Queensland, from a 

 bed of limestone interstratified in the Lower Cretaceous (Rolling 

 Downs) Formation, This particular piece of limestone was 

 selected for special examination because its surface had weathered 

 into a soft brown crust like Bath brick, closely resembling in this 

 respect the Middle Devonian radiolarian limestones of Tamworth, 

 N.S. Wales. An examination for radiolaria of thin sections of 

 this rock under an inch objective proved disappointing, and the 

 sections were put aside, but on being re-examined about two 

 months ago with a \ inch objective with a view to studying the 

 nature of the network of a fragmental radiolarian shell, it was 

 observed that numerous black particles, which under the lower 

 power appeared structureless, now showed definite structure. 



