EXPLANATION OF PLATE 25 



Fig. A. Showing the ideal type of spherulite. The number of plates of 

 feldspar that make up the spherulites are so small and are in such large numbers 

 that the outline of each individual plate is not visible. X 230. 



Fig. B. Showing the spherulites in the ground-mass and in the altered rem- 

 nants of phenocrysts. The prismoid crystals that make up the spherulite are 

 microscopic in size and do not give a black cross under crossed nicols. X 60. 



[380] 



