24 Proceedings of the Royal Society of Victoria. 



in some reddish tufaceous matter, and may have been transported 

 either by the aborigines or Ijy natural means. The external 

 saucer consists of compact obsidian, of a bottle-green colour, and 

 is filled with finely-cellular black lava, much less transparent 

 and glassy than the obsidian." 



Darwin also mentions some obsidian balls described by F. S. 

 Beudant,^ which are never more than six or eight inches in 

 diametei', and are found strewn over the surface of the ground. 

 Their form is always oval ; sometimes they are much swollen in 

 the middle, and even spindle-shaped. Their sui'face is regularly 

 marked with concentric ridges and furrows, all of which on the 

 same ball are at right angles to one axis ; their interior is 

 compact and glassy. Beudant supposes that masses of lava, 

 when soft, were shot into the air, with a rotatory movement 

 round the same axis, and that the form and superficial ridges of 

 the bombs were thus produced. 



The Rev. W. B. Clarke,'^ in speaking of the specimen described 

 by Darwin, says that it would seem either to have been drifted 

 from a very long distance, or, which is more likely, from the 

 known habits of the aboriginals, to have been dropped by one of 

 them, who probably found it in the trap hills of the Lachlan, 

 to the north eastwai'd. This specimen was unique as to Australia 

 until recently (at time of writing). The first which Mr. Clarke 

 met with was found in the cradle of a gold-washer on the Turon 

 River, who dug it from a depth of thirty feet below the surface. 

 A somewhat similar specimen was found in the washing-stufi" of 

 the Uralla or Rocky River, county of Hardinge, New England 

 District. From the same locality two other specimens were 

 derived. They appear as if they had been cast in a mould ; but 

 there is no reason to doubt the imputed origin. 



With regard to the Uralla specimens, Mr. Clarke thinks it 

 possible, from the contour of the country and the geological 

 structure, that they had their origin in an outburst of trap 

 (basalt) which caps the ranges in the neighbourhood, and has 

 issued from and overflowed the granite. He considers this more 

 satisfactory than associating them with an intrusion of various 



1 Voj'age Miiuralogiciue et Goologique en Hoiiyrie, ISIS, toni. ii., p. '214. 



2 On the Occurrence of Obsidian Bomlis in the Auriferoiis Alluvia of N.S.W. Quarterly 

 Jour, of Geol. Soc, vol. xi. (1855), p. 403. 



