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RECORDS OF THE AUSTRALIAN MUSEUM. 
special knowledge, is particularly valuable — it was agreed that the 
moth represented sitting on a tree-trunk forcibly reminded one of 
the head of the tree lizards, members of the genus Varanus. An 
example is depicted on the plate. It is the “eye” on the wing of the 
moth that strikes the key-note of the situation ; but in addition 
the shape of the wing, when the moth is resting, looks very 
suggestive. The moth is one which passes its larval state in the 
butts of Eucalyptus trees for the period of live or six years, but 
on emergence the perfect insect is not prone to Jiy, and would 
therefore be very liable to be attacked by birds. Hence the 
probability that my surmise of the striking resemblance to the 
head of the lizard being an instance of genuine protective imitation 
is correct. 
The reptile photographed was not very specially selected, and 
others might perhaps have been used wherein certain features 
were more strongly marked. For instance, many members of the 
genus Varanus have a dark line passing from the eye backwards. 
In conclusion, it might be well to point out that the marks on 
the outer margin of the visible wing of the moth are very 
suggestive of labials, while the various lines in front savor of the 
regularity of scales. Some of these tree-lizards and the moth 
are natives of New South Wales. 
The log from which the moth figured emerged was collected near 
Newcastle, by Mr. W. Kershaw, late of the Melbourne Museum, 
and kindly presented to this Museum, thus affording us an 
opportunity of observing the living moth in its natural position 
and development. 
Some SUGGESTIONS REGARDING the FORMATION of 
“ENHYDROS” or WATER-STONES. 
By T. Cooksey, Ph.D., B. Sc. 
(Mineralogist to the Australian Museum.) 
The mode of formation of these interesting bodies is still in 
considerable doubt, and therefore it seems to the writer that 
these notes attempting to explain their occurrence will not be 
without interest. 
Mr. E. J. Dunn has given a description of the characters of 
those specimens which he obtained from Spring Creek, Beech worth, 
