Similar examples can be found in the collections of the V&A (C.225&A-1912), the Smithsonian (e.g. Arthur M. Sackler Gallery, S2012.9.3042a-b) and the Indianapolis Museum of Art (2001.365/2001.366).
For similar vases in He Li, Chinese Ceramic, The New Standard Guide From the Asian Art Museum of San Francisco, London 1996, no. 370 and in Wu Hung, The Art of the Yellow Springs, Honolulu 2010, p. 160.
Pairs of Mingqi vases were used to contain offerings of rice for the deceased in tombs. On this pair, the finials refer to the Vermillion Bird of the South (Nan Fang Zhuque), a mythological creature that represents the element of fire in Daoist belief. Like the phoenix in western mythology, the Vermillion Bird is said to be reborn from flames; its popularity as a motif on funerary wares is perhaps owing to such connections with immortality. In Daoism, every living being has two types of soul; the ethereal hun (魂 ‘cloud soul’), which leaves the body after death, and the corporeal po (魄 ‘white soul’), which remains within the deceased. Placing food and goods for the comfort and nourishment of the po in graves was popularised during the Han Dynasty, but continued throughout the Song.
For further information on Qingbai burial jars from this period see:
Qingbai Ware: Chinese Porcelain of the Song and Yuan Dynasties (ed. Stacey Pierson, PDF, 2002) p.180
Chinese Ceramics from Datable Tombs (J.M. Addis, Sotheby Parke Bernet, 1978) pp.34-36.