92 RECORDS OF THE AUSTRALIAN MUSEUM. 



special kno\yledge, 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 Varamifi. 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 

 suggescive. 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 tly, 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. AV. 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" oh 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, 



