Dolmens are generally found either on the top of a natural or an artificial mound, in the middle of a plain, or on the banks of a watercourse. We must mention, amongst others, those in Persia, which are some 7,000 feet high and from twenty-one to twenty-six feet long by six wide; that near Mykenæ, that of Aumède-Bas, excavated by Dr. Prunières; that of New Grange, in Ireland, surmounted by a cromlech of stones of considerable size, many of them brought from a distance; that of Hellstone, near Dorchester, consisting of nine upright stones supporting a table more than twenty-seven and a half feet in circumference, seven feet wide and two and a half thick. The dolmens near Saturnia, one of the most ancient Etruscan towns, include a quadrangular room, sunk some feet into the earth, and having walls made of blocks of stone and a roof of a couple of large slabs, sloped slightly to let the rain run off. We give illustrations of the dolmens of Castle Wellan in Ireland (Fig. 55), of Coreoro near Plouharnel (Morbihan) (Fig. 56), of Arrayolos in Portugal (Fig. 57), and Acora in Peru (Fig. 58), which will enable the reader to judge of the different modes of construction employed in building these megalithic monuments. [Illustration: 58.] Megalithic sepulchre at Acora (Peru). In some cases the dolmen, which alone is visible from without, is placed upon a mound, covering a hidden sepulchral chamber, whilst in others the crypt is replaced by a simple stone cist, generally of rectangular shape. We may mention in this connection the dolmen of Bekour-Noz at St. Pierre Quiberon, which is remarkable for its great size, and rises from the midst of a cemetery in which a great many coffins have been found. The bones they contained were unfortunately dispersed at the time of their discovery. Dolmens are scattered about in great numbers in the Kouban basin and all along the coasts of the Black Sea occupied by the Tcherkesses. These curious vestiges of an unknown civilization are still an unsolved enigma to us, as are those of Western Europe; they are generally formed of four upright slabs surmounted by a fifth laid horizontally, and one of the supporting slabs is nearly always pierced with a small round or oval opening. Excavations have brought to light arrow-heads, rings, and bronze spirals, but Chantre, an authority of considerable weight, and who has moreover had the advantage of actually seeing these megalithic monuments of the south of Russia, attributes the objects found beneath them to secondary interments, and does not hesitate in assigning the more ancient monuments themselves to the Stone age. We must not omit to mention the dolmens found in the southern portion of the island of Yezo (Japan),4 nor that described by Darwin at Puerto Deseado (Patagonia). They are both very similar to those of Europe.