Dragon-form roof ornaments of this type, known as chiwen (owl's lips), were placed either side of a roof ridge so that their open jaws appear to be biting the end of the ridge. According to legend, the abode of these half-fish, half-dragon-like monsters was the Eastern Sea. As rain was supposed to occur when water spouted from their jaws, there were used as a charm against fire.
For an ornament of this type, the large dragon overlaid with the body of a smaller dragon, but glazed in a palette of purplish-blue, turquoise and yellow see d'Argencé, ed., Chinese, Korean and Japanese Sculpture in the Avery Brundage Collection, Japan, 1974, no. 172. See, also, the example sold in our Los Angeles rooms, 7 May 1999, lot 112.