MICROSCOPIC STRUCTURE OF SOME AUSTRALIAN ROCKS. 185 



of Mitchell near Bathurst — Rec. Geol. Survey N. S. Wales, 



Vol. i., p. 16. 



David, T. W. E. — Notes on a collection of Igneous Rocks 



from Lord Howe Island — Mem. Aust. Museum, Sydney, No. 6. 



David, T. W. E., and Anderson, W. — The Leucite-Basalts of 



New South Wales — Rec. Geol. Survey N. S. Wales, Vol. I., 



Part iii., p. 153. 

 1890. Ross, W. J. C— The Plutonic and Metamorphic Rocks of 



Bathurst, New South Wales — Proc. Austr. Assoc. Adv. Sci., 



Vol. ii., p. 420. 



Hut ton, F. W. — On the Granites and Associated Rocks of the 



Upper Buller River, New Zealand — Trans. Geol. Soc. Aust. 



Vol. i., p. 99, Melbourne, 1890. (Read 8th July, 1887). 



Hutton, F. W. — Description of some Eruptive Rocks from 



the neighbourhood of Westport New Zealand — Ibid, p. 106. 



(Read 10th October, 1887.) 

 I have endeavoured to refer each rock to its natural place in 

 the most approved system of classification. There is a decided 

 tendency, on the part of Petrologists, to follow Professor Rosen- 

 busch, whose splendid, and lucid works are now so accessible. Of 

 course I follow the British as opposed to Continental Geologists, 

 in refusing to make the age of a rock an essential character in its 

 nomenclature. Short comings have been pointed out in every 

 system, but the actual name matters little, after all, when we 

 understand the sense in which it is used. There can be no con- 

 fusion, for instance, when I term the holo-crystalline pyroxene 

 rocks of Carcoar, Gabbro, provided it is clearly explained that I 

 use that term in the sense it is employed by Professor Judd.* 

 Even with these precautions a great deal must still be left to the 

 individual views of each Petrologist. As Professor Bonney puts 

 it,f "What is seen with the microscope depends not only on the 

 instrument and the rock-section, but also upon the brain behind 



* See Professor Judd's paper On the Gabbros etc. of Ireland and Scot- 

 land — Quart. Journ. Geol. Soc, Vol. xlii., p. 61. 



f Anniversary Address to the Geological Society, 1885 — Quart. Journ. 

 Geol. Soc., Vol. xli., p. 59. 



