On Extensive Infusoria Deposits. 141 



Akt. XVII. — On Extensive Infusoria Deposits in the Mallee 

 Scrub, near Swan Hill, on the Lower Murray River, in 

 Victoria ; and, on the Presence of Fucoidae in Silurian 

 Rocks, near Melbourne. By Wellliam Blandowski, Esq. 



WITH ONE PLATE. 



[Read before the Institute, 11th November, 1857.] 



When passing Swan Hill, on my late excursion to the Lower 

 Murray, Mr. Beveridge drew my attention to an extraordinary 

 geological formation in the Mallee Scrub. He accompanied me 

 in the middle of summer for about twenty or twenty-two 

 miles, in a westerly direction from his residence. We travelled 

 under a burning sun ; not a single drop of water was to be 

 found on the whole journey, but only dense bushes of Eucalypti 

 dimosse, with low sandy limestone ranges alternating with 

 dried up grassy open patches of good land, sometimes of a few 

 miles in extent, which relieved the weary minds of the riders. 

 Now and then a Leipoa started from the dense brushes, or a 

 lizard from the sandy places, but not a single kangaroo inter- 

 rupted the monotony of the scene: The rapidity with which we 

 rode compelled us to keep a sharp look-out for all branches and 

 crooked stems of the Mallee Scrub, to avoid serious accidents. 

 We, nevertheless, arrived sooner at our destination than I had 

 expected. 



Here, low dry channels wound their course to the N\W. for 

 an apparently indefinite distance, through a dreary-looking 

 country, in which scarcely any vegetation covered the sterile" 

 slightly undulating ground. Suddenly our horses were plunging 

 through a brownish black crust into a pale yellow mass of flour- 

 like mineral. Clouds of dust surrounded horses and riders, 

 leaving a deep track behind along their route, similar to that 

 we should have made on crossing a slightly frozen shallow 

 lagoon. Every step of our horses formed a separate mark on 

 the ground. I examined the mass under our feet. I dug with 

 my hands a deep hole and tied up about twenty pounds of it in 

 my pocket handkerchief, and sent a bagful as a specimen for our 

 National Museum, which was delivered some time ago to that 

 Institution, and numbered 1172. 



I recognised in this flour-like, fine powdered earthy mass of a 

 pale yellow uniform colour, the well-known " Kieselguhr" or 

 " Bergmehl," of the German mineralogists ; but, not having a 



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