Edouard Lartet, in 1860, began exploring the caverns of the Pyrenees and of Périgord, first examining the remarkable cavern of Aurignac with its burial vault, its hearths, its reindeer and mammoth fauna, its spear points of bone and engravings on bone mingled with a new and distinctive flint culture. This discovery, published in 1861,(28) led to the full revelation of the hitherto unknown Reindeer and Art Period of the Old Stone Age, now known as the Upper Palæolithic. As a palæontologist, it was natural for Lartet to propose a fourfold classification of the 'Reindeer Period,' based upon the supposed succession of the dominant forms of mammalian life, namely: (_d_) Age of the Aurochs or Bison. (_c_) Age of the Woolly Mammoth and Rhinoceros. (_b_) Age of the Reindeer. (_a_) Age of the Cave-Bear. Lartet, in association with the British archæologist, Christy, explored the now famous rock shelters and caverns of Dordogne--Laugerie, La Madeleine, Les Eyzies, and Le Moustier--which one by one yielded a variety of flint and bone implements, engravings and sculpture on bone and ivory, and a rich extinct fauna, in which the reindeer and mammoth predominated. The results of this decade of exploration are recorded in their classic work, _Reliquiæ Aquitanicæ_.(29) Lartet, observes Breuil,(30) clearly perceived the level of Aurignac, where the fauna of the great cave-bear and of the mammoth appears to yield to that of the reindeer. Above he perceived the stone culture of the Solutrean type in Laugerie Haute, and of the Magdalenian type in Laugerie Basse. Lartet also distinguished between the archæological period of St. Acheul (= Lower Palæolithic) and that of Aurignac (= Upper Palæolithic). It remained, however, for Gabriel de Mortillet, the first French archæologist to survey and systematize the development of the flint industry throughout the entire Palæolithic Period, to recognize that the Magdalenian followed the Solutrean, and that during the latter stage industry in stone reached its height, while during the Magdalenian the industry in bone and in wood developed in a marvelous manner. Mortillet failed to recognize the position of the Aurignacian and omitted it from his archæological chronology, which was first published in 1869, _Essai de classification des cavernes et des stations sous abri, fondée sur les produits de l'industrie humaine_:(31) (5) _Magdalénien_,[K] characterized by a number and variety of bone implements; (4) _Solutréen_, leaf-like lance-heads beautifully worked; (3) _Moustérien_, flints worked mostly on one side only; (2) _Acheuléen_, the 'langues de chat' hand-axes of St. Acheul; (1) _Chelléen_, bold, primitive, partly worked hand-axes.