Referring to an undivided tarsal sheath, i.e. one not consisting of separate scales or scutes <ref name="Kenya">Zimmerman, Dale A.; et al. (1999). Birds of Kenya and Northern Tanzania. Princeton University Press. p. 432. ISBN0691010226.</noinclude>.
Reference[]
This article is part of Project Glossary, an All Birds project that aims to write comprehensive articles on each term related to animals.