ILLUSTRATIONS 



IX 

 Page 



Swartz : 



Figure 4 — Axis of symmetry developed at intersection of symmetry 



planes 372 



" 5 — Alternating axis developed by alternating axes and sym- 

 metry planes 372 



6 — Axial class 374 



7 — Polyaxial class 374 



8 — Orthoaxial class 374 



9 — Repetition of singular axis by oblique plane of symmetry. 374 



10— Hedral class 374 



11 — Orthohedral class 376 



12 — Amebahedral class 376 



13 — Amebaxial class 376 



14 — Three-fold alternating axis producing orthohedral sym- 

 metry 376 



Carney : 



Figure 1 — Kelleys island, Ohio 641 



Swartz : 



Figure 1 — Sections of Jennings formation, western Maryland 681 



Durand : 



Figure 1 — Proposed form of seismograph 709 



(111 plates, 35 figures) 



