A critical summary of the conclusions of a number of recent papers on Permian and Triassic tetrapods, mainly Reptilia. These papers are by J. A. Efremov on Russian forms, A. S. Romer and L. W. Price on Pelecosauria, mostly American, G. G. Simpson on Multituberculata, C. C. Young on Chinese forms, and T. E. White on Seymouria. A correlation table of vertebrate horizons in Texas, Russia, and South Africa is included.

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