which were entirely new. This was followed by numerous accounts of mammals, birds, and reptiles, which were largely inspired by the study of the specimens which Alcide de Orbigny, Eydoux, Soleyet, Castelnaud, and other travelers brought back from their long voyages. The examination of the series of birds led him to general conclusions respecting their natural division. These conclusions, drawn from the character of the skeleton, and particularly of the sternum, have been widely accepted. He interested himself in the study of the geographical distribution and classification of reptiles, in the course of which he made various investigations upon the batrachians, particularly the salamanders and tritons. In connection with his researches in the fishes, he was in charge for twenty years of the administration's experiments in pisciculture in the department of Hérault, the chief object of which was to acclimatize the true salmon, species which were not known to exist in any of the streams emptying into the Mediterranean. In co-operation with M. Walckenaer, he prepared a "Natural History of Wingless Insects" ("Histoire naturelle des Insectes aptères").
M. Gervais's first work in paleontology was the thesis which he prepared for the degree of Doctor in Science, on fossil birds. In it he demonstrated the existence, in the Tertiary period, of birds belonging to several genera common in the present age. Cuvier had proceeded in this line of investigation hardly further than to give approximately the order, and in only a few cases the possible genus to which his specimens might belong. M. Gervais, having better material at his command, was able to make more precise determinations.
In fossil mammalia he made known a new simian, the Semnopithecus monspessulanus, a hyena, several deer, a porcupine, and numerous cetaceans. His memoir on the distribution of the fossil mammalia among the several Tertiary beds of France deserves particular mention. It exhibited the association of the different species among the various faunas that succeeded one another, from the earliest Tertiary epoch, corresponding with the lignites of the Soissonais to the period of the large animals whose remains are found in the breccia of the caverns. The author shows that these different faunas, which he makes to number seven, never lived simultaneously, either in France or any other country, and that no species was common to more than one of them. The fauna which left its bones in the breccia is the only one which is not entirely extinct. Some of these faunas present only animals of terrestrial species, while others furnished in some of the beds both marine and land species. This feature gave useful indications for determining by the comparison of the land species buried in the marine beds with those which are found at other places in fresh-water deposits, the contemporaneity of land and marine animals for each epoch. It also enabled M. Gervais to determine, under certain conditions, the comparative age of the two kinds of formations. Contrary to the opinion of some
