Report of National Museum, 1890.— Mernl 



Plate CXXVII. 



Fig. 1. Quartz porphyry showing porphyritic structure. (Cat No. 35953, U. S. N. M.) 

 Fig. 2. Quartz porphyry showing flow structure. (Cat. No. 35946, U. S. N. M.) 



