555 



extensive studies on the subject <>t inclusions ami assistance 

 in the dihVult determination of some decomposition pro- 

 ducts. Mr. L. L. Waterhouse has allowed me to use his 

 measurements of the aragonite crystals. To all these 

 gentlemen I tender my hearty thanks. 



Description of Plate XXXIV. 



2. Pseudoporphyritic structure in dunite, probably due to 



differential granulation. Polarised light, x 18. 



3. Intergrowth of pleonaste and augite in gabbro porphyry. 



Ordinary light. x 18. 



4. Serpentine after dunite. Polarised light. x 25. 



5. Junction of gabbro and basalt, showing differential 



absorption of the minerals of the gabbro by the 

 basalt magma. Ordinary light. x 8. 



6. Hyalopilitic basalt in the Hornsby volcanic breccia. 



Ordinary light. x 32. 



(Photomicrographs by H. G. Gooch.) 



