304 AUSTKALASIAN ANTARCTIC EXPEDITION. 



The types are probably derived from sediments whose composition has been 

 modified by igneous emanations. Such origin is rendered the more likely by the final 

 type which is rich in tourmaline as well as magnetite. 



Measurements of pleochroic halos and nuclei have been made in both cordierite 

 and biotite. The formation of these halos has been ascribed partly to Th C, partly to 

 Th X and Ra A. 



In conclusion, the writer desires to thank Professor W. W. Watts, of the Royal 

 School of Mines, South Kensington, for kind assistance in the prosecution of research, 

 and he is also specially indebted to Dr. F. L. Stillwell, at whose suggestion the work 

 was undertaken and who has given the writer every possible assistance and unhesi- 

 tatingly helped with his great experience of Adelie Land specimens. 



