Shau Yuting, a native of Yixing, was a renown potter who was active in the Republic era (Post 1911).
This teapot was made according to the shape of an ancient bell using fine zishz clay (as commented by Prof Pan CF).
I acquired this pot in the 80s in an antique shop in Singapore. When Prof Pan was in Singapore in 1992, I let him evaluate this pot for me. He confirmed that the pot was made around the republic time using fine zisha clay. He also commented the workmanship is superb, a very good Yixing zisha pot indeed.