CUCULID^ — THE CUCKOOS. 469 



The three families next in order are those generally known as the Zygodac- 

 tyli, in their more restricted sense, that is, having the toes arranged in pairs, 

 two before and two behind. In tlie 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 the Trogonidm, the Bucconidce, and the 

 Gcdhuilidcc, which likewise have the toes in pairs, but in which they are dif- 

 ferently combined. 



The North American families, the Cuculidce, the Picidoe,BJid the Psittacidoe, 

 are defined as follows : — 



A. Upper mandible not movable nor hinged. Tarsus with transverse scutellse. 

 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 Cuculidce. 



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 ham- 

 mering. Thick nasal tufts at base of the bill (except in the Nudinares) . 



Picidce. 



B. Upper mandible movable or hinged. Tarsus without transverse scutellte. 

 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 Psittacidoe. 



