Fig. 6. — Pyromeride showing shape of enclosed quartz-mass (dotted);. 



from Boulay Bay. 



[Nat. size.] 



The two lower figures show the extension of the quartz in two planes at 

 right angles to that of the upper figure. 



Fig. 7. — Pyromeride from Boulay Bay. (The right-hand figure 

 represents a section taken across the left-hand one.) 



[Nat. size. As in the other figures, the dotted areas represent quartz.] 



Fig. 8. — Diagram of elongated gas-vesicles in pyromeridal rocJc. 

 (From harbour of Boulay Bay.) 



[Slightly more than nat. size.] 



[f nat. size.] 



