V. 2.rn18. The Cambrian period / S. Peng, L.E. Babcock and R.A. Cooperrn19. The Ordovician period / R.A. Cooper and P.M. Sadlerrn20. The Silurian period / M.J. Melchin, P.M. Sadler and B.D. Cramerrn21. The Devonian period / R.T. Becker, F.M. Gradstein and O. Hammerrn22. The Carboniferous period / V.I. Davydov, D. Korn, M.D. Schmitzrn23. The Permian …