The “sacrificial stone,” so called, which also stands in the court-yard of the Museum, was not one of the ordinary altars on which victims were sacrificed. These altars seem to have been raised slabs of hard stone with a protuberant part near one end, so that the breast of the victim was raised into an arch, which made it more easy for the priest to cut across it with his obsidian knife. The Breton altars, where the slab was hollowed into the outline of a human figure, have some analogy to this; but, though there were very many of these altars in different cities of Mexico, none are now known to exist. The stone we are now observing is quite a different thing, a cylindrical block of basalt nine feet across and three feet high: and Humboldt considers it to be the stone described by early Spanish writers, and called _temalacatl_ (spindle-stone) from its circular shape, something like a distaff-head. Upon this the captive chiefs stood in the gladiatorial fights which took place within the space surrounding the great teocalli. Slightly armed, they stood upon this raised platform in the midst of the crowd of spectators; and six champions in succession, armed with better weapons, came up to fight with them. If the captive worsted his assailants in this unequal contest, he was set free with presents; but this success was the lot of but few, and the fate of most was to be overpowered and dragged off ignominiously to be sacrificed like ordinary prisoners. On the top of the stone is sculptured an outline of the sun with its eight rays, and a hollow in the centre, whence a groove runs to the edge of the stone, probably to let the blood run down. All round it is an appropriate bas-relief repeated several times. A vanquished warrior is giving up his stone-sword and his spears to his conqueror, who is tearing the plumed crest from his head. The above explanation by Humboldt is a plausible one. But in Central America altars not unlike this, and with grooves upon the top, stand in front of the great stone idols; and this curious monument may have been nothing after all but an ordinary altar to sacrifice birds and small animals upon. [Illustration: THREE VIEWS OF A SACRIFICIAL COLLAR, _Carved out of hard mottled greenstone. (In Mr. Christy’s Collection.) This is 17 inches long, and varies from 11 to 16 inches in width. The arms are 4 inches wide and 3 inches deep; and are 8 inches apart at about half their length._] Señor Leon Ramirez, the curator, had come to the Museum to meet us, and we went over the collection of smaller objects, which are kept up stairs in glass-cases,—at any rate out of the way of the soldiers.