14. =Gnathotheca.= The covering of the lower jaw.

15. =Cere= (_Cera_, or _Ceroma_). A skin at the base of the

maxilla, in certain birds. (In birds without a horny sheath to the

bill, the cere may be considered as extending to its very tip.)

16. =Edges of bill= (_Tomia_). The margins of upper and lower jaws

where they come in contact. We have thus a

A History of North American Birds; Land Birds; Vol. 3 of 3 · 第 286 / 607 题