An importer of dinnerware and glassware, Ucagco (United China and Glass Company) was founded in 1850 by Abe Mayer and originally called Abe Mayer & Co  They had offices in New York and New Orleans and did business throughout the Southeast U.S. as well as Central and South America. It wasn't until the 30s that the company took on the official trademark of UCAGCO and began expanding overseas. In fact, after the war, the company's agent in Japan, S.A. Stolaroff signed the very first contract allowing imports from Japan. A talented ceramic designer himself, Stolaroff worked alongside many Japanese potteries to lead the company's line of ceramics. In 1956, UCAGCO was sold to Sammons Enterprises and in 1962, Stolaroff, who had become the company's president, retired.   The pieces feature both transfer-type marks and paper labels.

PY made a number of things that they distributed to other manufacturers to sell under their label.  Here is a PY mermaid with the Ucagco label.