Contents: I; pt. 1. On the anatomy and affinities of the genus Pterygotus. By T. H. Huxley, pt. 2. Description of the species of Pterygotus. By J. W. Salter. 1859; II. On the structure of the Belemnitide: with a description of a more complete specimen of Belemites than any hitherto known, and an account of a new genus of Belemitidae, Xiphothuethis, by T. H. Huxley. 1864; III. The Crocodilian remains found in the Elgin sandstones, with remarks on the ichnites of Cummingstone. By T. H. Huxley. 1877; IV.