The three families next in order are those generally known as theZygodactyli, in their more restricted sense, that is, having the toes arranged in pairs, two before and two behind. In the present case the anterior toes are the inner and the middle (the second and third), the posterior being the hinder and outer (the first and fourth); where, as is sometimes the case, a hind toe is wanting, it is the first, or the hind toe proper.By this definition we exclude theTrogonidæ, theBucconidæ, and theGalbuilidæ, which likewise have the toes in pairs, but in which they are differently combined.The North American families, theCuculidæ, thePicidæ, and thePsittacidæ, are defined as follows:—A.Upper mandible not movable nor hinged. Tarsus with transverse scutellæ. Bill without a naked skin, or cere, at the base; lower mandible much longer than deep, the end not truncated.a.Tongue short, and not extensible; not barbed at the point.Bill hooked or curved at tip; not constructed for hammering. No nasal tufts…Cuculidæ.b.Tongue long and cylindrical, and generally capable of great extension; barbed at the point.Bill not hooked, but nearly straight; strong, and constructed for hammering. Thick nasal tufts at base of the bill (except in theNudinares)…Picidæ.B.Upper mandible movable or hinged. Tarsus without transverse scutellæ. Bill with a naked skin, or cere, at the base; lower mandible not longer than deep, its end truncated.c.Tongue short and thick, fleshy.Bill enormously large, much curved, the upper mandible hooked, both much arched…Psittacidæ.
The three families next in order are those generally known as theZygodactyli, in their more restricted sense, that is, having the toes arranged in pairs, two before and two behind. In the present case the anterior toes are the inner and the middle (the second and third), the posterior being the hinder and outer (the first and fourth); where, as is sometimes the case, a hind toe is wanting, it is the first, or the hind toe proper.
By this definition we exclude theTrogonidæ, theBucconidæ, and theGalbuilidæ, which likewise have the toes in pairs, but in which they are differently combined.
The North American families, theCuculidæ, thePicidæ, and thePsittacidæ, are defined as follows:—
A.Upper mandible not movable nor hinged. Tarsus with transverse scutellæ. Bill without a naked skin, or cere, at the base; lower mandible much longer than deep, the end not truncated.
a.Tongue short, and not extensible; not barbed at the point.
Bill hooked or curved at tip; not constructed for hammering. No nasal tufts…Cuculidæ.
b.Tongue long and cylindrical, and generally capable of great extension; barbed at the point.
Bill not hooked, but nearly straight; strong, and constructed for hammering. Thick nasal tufts at base of the bill (except in theNudinares)…Picidæ.
B.Upper mandible movable or hinged. Tarsus without transverse scutellæ. Bill with a naked skin, or cere, at the base; lower mandible not longer than deep, its end truncated.
c.Tongue short and thick, fleshy.
Bill enormously large, much curved, the upper mandible hooked, both much arched…Psittacidæ.