U. S. GEOLOGICAL SURVEY 



MONOGRAPH XXXI! PART 'II PL. LVI 



(A) x 13 



(B) x 20 



fCj x 12 



(D) x 12 



PHOTOMICROGRAPHS OF SPHERULITIC STRUCTURES AND FELDSPAR MICROLITES 



THE MELIOTYPE PAINTINO CO., BOSTON 



