Vol. 6, 1920 
PETROLOGY: G. P. MERRILL 
455 
phenocrysts within the chondrule and near the border are often cut off 
sharply as though the sphere, originally much larger, had been uniformly 
reduced by abrasion. This will be referred to later. 
FIG. 9 
III. Holocrystalline Chondrules. — As would naturally be expected, these 
porphyritic forms, through a reduction of the proportional amount of glass, 
pass gradually into those which are almost or quite holocrystalline and 
poly somatic as shown in figures 9 and 10 from the Barratta and Elm Creek 
FIG. 10 
stones respectively. Of peculiar interest are those of the polysynthetically 
twinned pyroxene (fig. 10). For some unexplained reason, these rarely 
grade into the half glassy porphyritic forms, the entire chondrule consist- 
