Even a large cavern like Combarelles offers comparatively few surfaces favorable to these engraved lines; but, small or large, such surfaces were eagerly sought, sometimes near the floor, sometimes on the walls, and again on the ceilings; even with the brilliant light of an acetylene lamp it is now difficult to discover all these outlines, some of which are drawn in the most unlooked-for places. If the extremely fine incisions, such as those representing the hair of the mammoth, are so difficult to detect with a powerful illuminant, one may imagine the task of the Crô-Magnon artists with their small stone lamps and wick fed by the melting grease. One such lamp has been found in the grotto of La Mouthe, about 50 feet from the entrance; the workman's pick broke it into four pieces, only three of which were recovered. The shallow bowl contained some carbonized matter, an analysis of which led Berthelot, the chemist, to conclude that an animal fat was used for lighting purposes. Like most other implements, this lamp is decorated--in this instance by an engraving of the head and horns of the ibex. Three of these lamps have been found in Charente and Lot, and it is noteworthy that lamps similar to those of the Magdalenian period are used in Dordogne at the present day. [Illustration: FIG. 204. Entrance to the cavern of La Pasiega, not far from Castillo. The seated figure with the staff is M. l'Abbé Henri Breuil, the present leader in the study of Upper Palæolithic art. Photograph by N. C. Nelson.] In the great cavern of Castillo,[AZ] at Puente-Viesgo, discovered in 1903 by Alcalde del Rio, which is entered by the majestic grotto already described on p. 162, the animal drawings are mostly of an archaic character, belonging to the very beginnings of early Aurignacian parietal art. The most abundant subjects are horses and deer, which entirely replace the reindeer drawings so abundant in central France, outlines of the stag and of the doe being very numerous; on the other hand, the bison and the ox are rarely drawn. Belonging to the category of most primitive painting are the simple outlines in black of a horse and of a mammoth, the two limbs of one side being represented as inverted triangles, terminating in a sharp point, like the drawings of children. Of more recent style are the rather crude polychrome bisons, numerous hands outlined in red, and a vast number of tectiform signs and symbols which represent inferior work of the middle Magdalenian period. [Illustration: FIG. 205. Carefully engraved half-figure of a bison, from the cavern of Marsoulas; an example of the engraver's work preceding the application of color. After Breuil. One-eighth actual size.]