To these "finds" we shall have reason later to refer more in detail, but of one thing we would speak here. An enormous quantity of lumps of copal, a resin obtained from several small trees or shrubs of tropical America with compound dotted leaves, known to botanists as the order of Burseraceae, have been dredged up. This copal was used as incense in the Mayan temples, and it is certain that it was regarded as very precious, for there is evidence that tributes to overlords were paid by vassal tribes in so much weight of this resinous gum. There thus seems little doubt that part of the ritual at the cenote edge was the casting in of lumps of copal as offerings to the god, and it is more than likely that this custom is referred to unconsciously by the Spanish official reporting in 1579, when he says that "all the followers of that lord and the lord himself threw great stones into the water and with loud cries fled from the place." The pieces of copal recovered are in some cases as large as a human head. About one hundred and thirty yards to the south-west of the great pyramid is the building known as the Tennis-Court. Running north to south are two immense parallel walls 274 feet long, 30 feet thick, 25 feet high, and 120 feet apart. At each end, some 30 yards from the walls, stand buildings roofless and wall-less on the Tennis-Court side. That on the north still shows traces of elaborate carvings from floor to roof, and on two pillars, where was once a doorway, are figure carvings. The building to the south is not so richly decorated. The clue to the purpose of this vast enclosure is given by a massive stone ring projecting from the eastern wall 20 feet from the ground. A corresponding one on the west side has fallen and lies among the bushes. We found its measurements to be 3 feet 11 inches in diameter, 11-1/2 inches thick, and the diameter of the ringhole 1 foot 7 inches. The ring still in position is obviously of the same measurements: it can be seen in the photograph reproduced. On the flat surface and on its edges each ring is carved with two serpents intertwined. These rings formed an essential part of a ball-game, which seems to have been common to the Mayan peoples in Yucatan and the Aztec subjects of Moctezuma in Mexico. The native name for this pastime was _Tlachtli_.