A field visit to the southern Appalachians mountains in 1948 with
Carl Gans was the start of his work on salamanders. On his retirement in 1998, his collection of approximately 140,000 salamander specimens was donated to the
Smithsonian Institution. Since 1999 he has been a member of the Committee on Standard and English Scientific Names for North American Amphibians and Reptiles. He is the author or co-author of over 90 scientific publications. ==Honours and awards==