This First Interglacial Stage is also known as the _St.-Prestien_, because among the many localities in France and Italy which preserve the plant and mammal life of the times that of St. Prest, in the Paris basin, is the most famous. Here in 1863 Desnoyers(10) first reported the discovery of a number of mammal bones with incision lines upon them, which he considered to be the work of man. These deposits were regarded at the time as of Pliocene age, and this gave rise immediately to a wide-spread theory of the appearance of man as early as the Pliocene. The human origin of the incisions discovered by Desnoyers has long been a matter of dispute and is now regarded as very improbable. Similar lines may be of animal origin, namely, marks left by claws or teeth, or due to accidental pressure of sharp cutting surfaces. However, we do not pretend to express an opinion of any value as to the cause of these incisions. Supposed confirmation of the evidence of Desnoyers of the existence of Pliocene man was the alleged finding by Abbott of several worked flints, two _in situ_, in the 'Forest Bed of Cromer,' Norfolk. Many years later in similar deposits at St. Prest were discovered the supposed 'eoliths' which have been referred to the _Étage Prestien_ by Rutot. The age of the St. Prest deposits is, therefore, a matter of the very highest interest and importance. [Illustration: FIG. 27. The giant deer (_Megaceros_), which first appears in western Europe during the First Interglacial Stage, probably as a migrant from the forested regions of Eurasia. After a painting by Charles R. Knight, in the American Museum of Natural History.] St. Prest is not Pliocene; it is rather the most ancient Pleistocene deposit in the basin of Paris,(11) and these incised mammal bones probably date from the First Interglacial Stage. The bed which has yielded the incised bones and the rich series of fossils consists of coarse river sands and gravels, forming part of a 'high terrace,' 98-1/2 feet (30 m.) above the present level of the river Eure. This, like other 'high terraces,' contains a characteristic First Interglacial fauna, including the southern mammoth (_E. meridionalis_), and Steno's horse (_E. stenonis_). We also find here other very characteristic early Pleistocene mammals, such as the Etruscan rhinoceros (_D. etruscus_), the giant hippopotamus of early Pleistocene times (_H. major_), the giant beaver of the early Pleistocene (_Trogontherium_), three forms of the common beaver (_Castor_), and one of the bison (_Bison antiquus_). This mammalian life of St. Prest is very similar to that of Norfolk, England; to that of Malbattu in central France, Puy-de-Dôme; of Peyrolles, near the mouth of the Rhône, in southern France; of Solilhac near Puy; of Durfort, Gard; of Cajarc, Lot-et-Garonne; and finally to that of the valley of the Arno, in northern Italy.