Cope, E. D. 1869. Synopsis of the Extinct Batrachia, Reptilia and Aves of North America.  Transactions of the American Philosophical Society, 14, 1–252. (Read September 18, 1868 and April 2, 1869. Preprints distributed August, 1869 (first state. i.e. the version with the head on the end of the tail), and distributed again after March, 1870 (second state, revised with the head on the end of the neck, but back-dated August, 1869).