PLATE XXXVI. 



Fig. a. 



(Sp. No. 32827. AVithout analyzer, x 38.) 



Photomicrograpli illustrating a rather exceptional form of spilosite Tvith white spots lying in 

 the fine-grained gronndmass. Albite, irith a very small amount of chlorite and epidote, forms the 

 spots. (Described, p. 206.) 



Fig. B. 



(Sp. No. 32827. With analyzer, x 38.) 



This is the same section as above, viewed between crossed nicols, showing the aggregate char- 

 acter of the spots of this spilosite. (Described, p. 206.) 



