In favor of the theory that the Pre-Chellean culture is as ancient as Second Interglacial times, we should consider the fact that in several localities palæoliths of Pre-Chellean if not of Chellean type have been recorded in association with the remains of a number of the more primitive mammals which we have described above as characteristic of Second Interglacial times. For example, at Torralba, Province of Soria, Spain, there has been discovered(1) an old typical Chellean camp site, containing abundant remains of the broad-nosed rhinoceros and of the southern mammoth, mingled with the remains of other mammals of very ancient type, identified as the Etruscan rhinoceros and as Steno's horse. Again, along the River Somme, near Abbeville, in the _gisement du Champ de Mars_,(2) it is said that Pre-Chellean and Chellean implements have been found in association with the Etruscan rhinoceros, Steno's horse, and very numerous specimens of the sabre-tooth tiger and of the striped hyæna. Moreover, in Piltdown, Sussex, Pre-Chellean flints and the Piltdown skull are said to have occurred in a layer containing a rhinoceros which may be identified with the Etruscan. If these very ancient species of animals are rightly recognized and determined, and if they are truly found as reported in close association in the same layers with Pre-Chellean and Chellean flints, the evidence may be considered as quite strong that the beginning of Chellean culture dates from Second Interglacial times; unless, indeed, it should prove that these primitive species of mammals survived into Third Interglacial times in certain favored districts. We should also consider the possibility that these more ancient animals, the sabre-tooth tiger, Steno's horse, the Etruscan rhinoceros, and the giant beaver, did not really belong in the same layer with these old palæoliths but were accidentally washed into this layer from other more ancient deposits. As a rule, it is the most recent animals which establish a prehistoric date, because we know that a palæolith cannot be older than the most recent mammal with which it occurs. [Illustration: FIG. 54. Western Europe during the extension of the ice-fields and glaciers (dots) of the Third Glacial Stage--a period of continental depression believed to have been less extensive than that of the Second Glacial Stage (see Fig. 25, p. 65). The line from Scandinavia to northern Africa corresponds to the section shown in Fig. 13, p. 37. Drawn by C. A. Reeds, after Geikie and Penck. (Compare Fig. 13.)] [Illustration: FIG. 55. Excavation at Chelles-sur-Marne, the Palæolithic station where Chellean flint implements were first discovered. We observe the very close, regular, and unbroken succession of the geological layers containing the Chellean, Acheulean, and Mousterian flints.]