As at Mounds B and C, the circular shape of the house at Mound D was outlined by an area of organically stained soil which extended upward from the house floor almost to the surface of the mound. The flanks of all three mounds were of light colored sand which contrasted sharply with the dark, circular house outlines. The only reasonable conjecture thus far advanced to explain this circumstance is that a low embankment of relatively clean sand had been piled against the exterior wall of each house. Thus when a house burned the embankment would remain standing, well above the house floor, as a sort of mold of the lower portion of the house. Then when a mound was erected over the burned house remains and the standing embankment, the outline of the house might appear in the mound fill as a cast of the house, delineated by the circular embankment. OCCUPATIONAL FEATURES House No. 4 was the only occupational feature discovered at Mound D. _House No. 4_ This house was circular in shape, with an exterior wall formed of upright poles, wattle, and clay daub. Post molds indicated that there were at least 27 of the upright poles in the exterior wall (Fig. 10). They were 0.3 to 0.6 feet in diameter at the base and were set about two feet apart on an average. An interior hearth near the center of the house was probably circular in shape and an estimated three to four feet in diameter. Its exact dimensions could not be determined because of disturbance by the pothole. No interior post molds were found. Remains of an extended entranceway on the west side of the house consisted in five post molds which outlined the two parallel sides of the entranceway. The entranceway was slightly less than three feet wide, and it sloped downward from the surface of the floodplain into the house pit. Burned poles and burned clay daub with wattle impressions showed that House No. 4 had been destroyed by fire. DISCUSSION Investigation of Mound D revealed that the following sequence of events had taken place. A round, Caddoan type of house (House No. 4) with an extended entranceway on the west side was built in a shallow, excavated pit on the south bank of Cypress Creek. Architecturally the house was quite similar to those at Mounds B and C. Sand was probably banked against the outside wall of the house to a height of somewhat more than a foot. After an unknown period of time the house was destroyed by fire, and then the house remains and the surrounding embankment of sand were buried beneath a mound of sandy soil. This duplicates essentially the events reconstructed for Mounds B and C, the only unique feature at Mound D being the pit in which the house was built. [Illustration: Fig. 10 HARROUN SITE 41 UR 10 PLAN OF HOUSE NO. 4 MOUND D post mold unexcavated burned area pothole]