Mound No. 15 was situated on the south bank of the Rio Hondo, about 5 miles from its mouth, near the village of Santa Helena. This was a conical mound 25 feet in height and 120 feet in circumference at the base. Excavation was begun at the summit of the mound, which was somewhat flattened. For the first foot the soil consisted of light-brown earth, which contained nothing of interest. [Illustration: FIG. 51.--Small cup-shaped vase from Mound No. 15.] [Illustration: FIG. 52.--Objects from Mound No. 15.] For the next 3-1/2 feet there were large blocks of limestone, the interstices between which were filled with limestone dust and débris. In these were found large quantities of potsherds, some well painted and polished, together with part of the inferior maxilla of a medium-sized carnivore, probably a puma. At a depth of 3-1/2 feet a number of stone flags, each nearly 5 feet in length and from 4 to 6 inches in thickness, were exposed; on removing these a small chamber appeared, of which the flags formed the roof. The walls of the chamber, or cist, were built of squared stones mortared together; it was 6 feet long, 6 feet high, and 4 feet broad; the floor was of light-brown, very fine river sand. On carefully removing the sand the following objects were brought to light at depths varying from 3 feet below the surface of the sand to the bottom of the chamber: (a) A small round, cup-shaped vase, shown in figure 51, painted bright yellow and finely polished. It is 10 cm. high by 8-1/2 cm. in its greatest diameter. On its outer surface are two grotesque monkey-like figures, the outline of one of which is shown in figure 52 _a_. (b) A small thin bowl of the shape shown in figure 52 _e_, painted yellow throughout, well polished, and ornamented exteriorly with geometrical devices in red and black. (c) A somewhat larger bowl than the next preceding, of the shape seen in figure 52 _f_. The geometrical ornamentation on the outer surface is executed in low relief, and was afterwards painted over. (d) A large circular plaque painted yellow throughout, 42 cm. in diameter. This plaque had been polished but shows considerable signs of hard usage before burial. (e) A plaque-like vessel, 9 cm. in height, with the design represented in figure 52 _d_, of a human face separated from a dragon's head by the Maya numeral 7, repeated around the outer surface of its rim. (f) A shallow plaque, 36 cm. in diameter, painted yellow throughout, and polished; on the inner surface of the rim are repeated twice, outlined in black lines, the bird and the curious mythological animal seen in figure 52, _b_, _c_. (g) A basin-shaped vessel, painted a deep reddish-brown and finely polished throughout, with a very attractive and intricate device of interlacing diamond-shaped figures around the inside of the rim. (h) A vessel closely similar to the preceding, but smaller and not so well polished. It was broken into a number of pieces when found.