The general uniformity of Acheulean workmanship in all parts of western Europe is an indication that these Neanderthaloid tribes were more or less migratory and that the inventions of new and useful implements, such as the lance-pointed coup de poing of La Micoque and the flint-flakes of Levallois, which probably originated at an especial centre, or perhaps even in the inventive mind of a single workman, became widely distributed and highly distinctive of certain periods. The development of the implements in different regions is so uniform as to prove that the evolution of the early Palæolithic cultures extended all over western Europe and that the various types or stages were essentially contemporary. FORMS OF ACHEULEAN IMPLEMENTS There is a close sequence between the coup de poing of the Chellean workers and its development into the finer and more symmetrical forms of the Acheulean. The latter, according to Obermaier,(36) is distinguished by the flaking of the entire surface, by the far more skilful fashioning, and by the really symmetrical almond form which is attained by retouching both the surface and the edges. This more refined retouch becomes the means of producing symmetrical instruments, with straight, convex, or concave cutting edges, as well as finer and lighter tools. [Illustration: FIG. 82. Illustrating the method of 'flaking' flint implements by direct or indirect blow with a hammer-stone.] The _early Acheulean_ industry belonged to a warm temperate climatic period and directly succeeds the Chellean, as shown in a most perfect manner in the quarries of the type station of St. Acheul on the Somme. In these earlier strata the prevailing forms of coup de poing are the 'pointed oval' and the 'lance-pointed,' the latter showing very simple chipping, a broad point, and a thick base. The oval coups de poing are smaller than the Chellean tools of the same kind, carefully fashioned on all sides and round the base, and very symmetrical; there are four distinct varieties of these: the almond type, oval almond-shaped, elongate oval, and subtriangular--the latter evolving into the finely modelled type of late Acheulean times. It may have been from these oval types that the disc form was finally evolved. [Illustration: FIG. 83. Illustrating the method of 'chipping' flint implements by pressure with a bone or wooden implement, to produce the finer retouch of the surfaces and edges.]