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, they were used as a charm against fire.
For an illustration of similar amber-glazed chiwen in situ, see W. Weng, The Palace Museum: Peking, Treasures of the Forbidden City, New York, 1982, pp. 78-79 and Yu Zhuoyun, Palaces of the Forbidden City, Hong Kong, 1982, p. 234, no. 302.