374 



NATURAL HISTORY OF BIRDS. 



FIG. 175. Syrinx of Piaya 

 cay ana, tracheo-bronchial. 



FIG. 176. Syrinx of 

 Centropus, pseudo- 

 bronchial. 



distance from the bifurcation they are replaced by semi-rings, the ends of which are 

 connected by the tympaniform membrane, which, therefore, is not continuous with 

 any of the tracheal rings. This condition in the cuckoos is similar to that of Steator- 

 nis, which is figured later on (page 385). The pseudo-bronchial syrinx, as we propose 

 to call it, is somewhat intermediate between the above two. At some distance down 

 the bronchi are the ends of the semi-rings, separated by a rather broad membrane, but 

 the rings between this and the actual bifurcation are not complete, and the narrow 

 space between their ends is filled by a strip of membrane, which connects the tympa- 

 num proper with the bifurcation, and 

 the lower tracheal rings which may 

 also be similarly incomplete, as shown 

 in Fig. 176. 



The true bronchial syrinx is only 

 found in two peculiar American forms, 

 Crotophaga and Guira, which also 

 agree in many external characters, for 

 instance, in being the only cuckoos 

 with eight tail-feathers, all the rest 

 having ten. These two are, therefore, 

 fairly entitled to sub-family rank. On 

 the other hand, the muscular formula 

 AXY+ is concomitant with a certain pattern of the inferior feather tract, as in the 

 cuckoos which have not the muscle B, the ventral tract of both sides is single and not 

 bifurcate. The sub-family thus characterized comprises the true Cuculinae, which 

 again falls in two groups, those of the New World with the inferior space reaching 

 quite to the symphysis of the mandible, an altogether peculiar arrangement, and the 

 Old World species in which it only reaches part up the neck. The pterylographic 

 peculiarities are contrasted in figures 177 and 178. However, on the whole, the clas- 

 sification of the cuckoos is in an unsatisfactory condition, and we therefore proceed to 

 the more interesting forms without committing ourselves to any limitation of the 

 minor groups. 



It is but natural to begin with the bird which is the cuckoo, from the sonorous 

 voice of which the whole family derives its name. The cuckoo (Cuculus canorus), in 

 different local forms occurring all over the Palaearctic region, and wandering far south 

 in winter, is astonishingly like, in external appearance, some of the smaller hawks, not 

 only in color, but also in its manner of flight, a resemblance which in Europe caused 

 the superstition that the young cuckoo in the autumn turns into a hawk. The male 

 bird is well represented in the accompanying cut ; the back is slaty blue, throat lighter 

 gray, rest of under side white with dusky cross-bars ; feet cadmium yellow, and bill 

 dusky, with the corner of the mouth yellow, as is also the eye. Some Oriental cuckoos 

 belonging to the nearly allied genus Hierococcyx carry the Accipitrine resemblance 

 still further, as the young birds have the dusky markings on the lower surface longi- 

 tudinal, as in many hawks and falcons, later on, like them, changing into a plumage 

 transversely barred. This similarity is not accidental, but evidently a case of protec- 

 tive mimicry, a supposition greatly strengthened by the fact that we know of some 

 small Malaccan cuckoos (Penthoceryx), rusty brown above, and white beneath, barred 

 with dusky, which, in size, color, and general habits most closely ape the appearance of 

 certain diminutive shrikes inhabiting the same country. Still more remarkable, if 



