148 



Hyalostelia Australis, the Anchoring Spicules of 

 an hexactinellid sponge from the ordovician 

 Rocks of the macDonnell Ranges, Central 

 australia. 



By R. Etheridge, Junr., Curator, Australian Museum, 

 Sydney, Honorary Fellow. 



[Contribution from the Australian Museum. "\ 



[Head July 13, 1916.] 

 Plate XVITI. 



In 1900 a small collection of MacDonnell Ranges fossils 

 was presented to the Australian Museum by the Department 

 of Mines, Adelaide. Amongst these was a small piece of red 

 fossiliferous quartzite, the weathered surface covered with 

 minute straight, white, rod-like bodies, and the same showing 

 in section on the fractured ends of the entire mass. This at 

 the time was put aside for further examination, and, as so 

 often happens in such cases, forgotten. 



These white, apparently rod-like bodies I take to be the 

 anchoring spicules of an Hexactinellid Sponge, and referable 

 to the genus Hyalostelia, Zittel ( = Pyritonema } McCoy 0-)). 



The existence of these spicules had already been recog- 

 nized in the rocks of the MacDonnell Ranges. At the 

 annual meeting of the Society, on October 17, 1893, Mr. W. 

 Howchin (2) "exhibited a fossil sponge, Hyalostelia, from the 

 Lower Silurian rocks of the MacDonnell Ranges, forwarded 

 by Mr. Thornton, of Tempe Downs. The only other site 

 where it is known to occur in South Australia is in the 

 Cambrian rocks at Curramuika." 



Professor R. Tate briefly referred in his account of the 

 Horn Expedition fossils to the occurrence of sponge rootlets 

 in quartzite at Finke Gorge. He described ( 5) them as 

 cylindrical casts, 1'5 mm. in diameter, extending through a 

 vertical thickness of four inches. Notwithstanding these 



0) McCoy: Ann. Mag. Nat. Hist,, vi. (2), 1850, p. 273. 



<2) Ho we'll in : Trans. Roy. Soc. S. Aus., xvii., pt. ii., 1893, 

 p. 355. 



(3) Tate: Report Horn Expdn. Central Austr., pt. iii., 1896, 

 p. 113. 



