Woodworth.— Joints. 
PLATE 4. 
(.Photographs by P. P. Sharpies.) 
Fig. 1. Feather-fracture on pelite. Mystic Fiver quarry. Length of speci¬ 
men, 190 mm. 
Fig. 2. Fragment showing joint-fringe with curved lateral fracture surfaces. 
The b-planes are wholly wanting in the joint-block on this side of 
the fringe. Quoddy, Me. Collected by N. S. Shaler. 
Fig. 8. Coarse feather-fracture, showing joint-plane composed of b-planes and 
c-fractures and exhibiting resemblance between feather-fracture and 
joint-fringe. Mystic Fiver quarry. Length of original, 70 mm. 
Fig. 4. Joint-plane, with joint-fringe, showing b-planes, and curved lateral 
cross-fractures; also shoulder at edge of joint-plane. (See Plate 2, 
figs. 3, 4, 10.) Mystic Fiver quarry. Length of original, 110 mm. 
Fig. 5. Joint-block, showing joint-plane, with joint-fringe springing out from 
edge. Mystic Fiver quarry. Length of original, 60 mm. 
