A CONTRIBUTION TO THE STUDY OF AUSTRALITES. 
25 
arc quite as accurately matched one to another as living animals. 
They may and do differ in size, but they might almost, as far 
as their shapes are concerned, have been turned out from an 
engineer’s workshop by a lathe, or at least as fine castings before 
turning. 
Mr. Dunn’s paper explaining his bubble hypothesis im- 
mediately appealed to me as affording a clear reason for a peculi- 
arity in each and every one of the different patterns, viz. : a very 
well marked ridge, sometimes almost sharp, running in a definite 
line round each. 
An Australitc, of whatever pattern it may be, is always 
larger on one side of this circumferential ridge than the other, 
as it naturally would be in the bleb of a bubble. Again, in the 
most common form, at any rate in Western Australia, there 
appears to be a broad ring of facets quite distinctly marked 
and separated from each other bv intervening raised lines forming 
a somewhat conical body bounded above and below by convex 
discs and looking unquestionably as if something had been 
chipped off all round between these discs, whilst in the best 
specimens of those not sand-worn there is a definite varnish or 
glaze, as if the surface of the body had been heated sufficiently 
to raise its temperature just to the point of fusion, thus taking 
off the sharpness of, but not obliterating the lines of , demarcation 
between the fracture facets (Plate XX. Fig. 11), while in others 
this fusion of the surface has gone so far as to obliterate all the 
fracture marks and dividing ridges (Plate XX, Fig. 12). The 
large hanging drop form of the inner side of Mr. Dunn’s button 
shape would be quite accounted for if the bleb were formed on 
the top, where it partially hardened, and the bubble would be 
attached to the sharp outer ridge, while when the bleb was below 
the surplus glass gravitating downwards would naturally collect 
where the loosely attached ring is found, (Plate XIX, Fig. x) 
This glaze more or less perfect is found, of course, upon 
some specimens of all the other forms, as well as the conical one. 
This theory also presents a very comprehensible reason why the 
patterns are so few and are so exactly duplicated. 
The mode of formation of the dumb-bell and other allied 
shapes is one of the difficulties brought against the bubble theory. 
It can be asserted with the most perfect assurance, however, 
that this hypothesis affords an explanation, and, as far as 1 
know, the only explanation, that will account for the curious 
fact that the two ends of the dumb-bells do not lie in the same 
plane, but are curved towards one another, the curvature being 
such as would naturally be caused by the convexity of a bubble, 
the shorter the dumb-bell or other long shape the greater the 
curve (Plate XX, Figs. 13 to 17). 
