274 STKUCTURE AND CLASSIFICATION OF BIRDS 



Of other cuckoos whose pterylosis has been studied ' Gaco- 

 mantis, Piaya, Saurothera, Diplopterus, Coccyzus, Chrysd- 

 Goccyx, and Coccystes agree in most points with Cuculus, 

 But in the American genera Piaya, Diplopterus, Saurothera, 

 and Coccyzus, the ventral tract is double from the very first 

 — that is to say, in the mandibular region. 



A more complicated pterylosis characterises certain other 



Fig. 135. — Pterylosis of Piaya cayana. Dobsal View. (An-Eif 

 Beddakd.) 



cuckoos. In the genus Gentrop-us the feathering upon the 

 throat is close and continuous, the two ventral tracts diverg- 

 ing at about the junction of the neck.and trunk. Each of these, 



' Beddaed, ' On the Structural Characters and Classification o£ the CuotoOs,' 

 P. Z. 8. 1885, p. 168 ; Shdeeldt, ' Contributions to the Anatomy of Geocoooyx,' 

 ibid. 1886, p. 966. 



