1885.] MR. F. E. BEDDARD ON THE CLCKOOS. 185 



detail, but agree in tlie main fact that the pectovnl tract is single 

 and not bifurcate. Cacoinantis and Cuculiis are in some respects 

 different from the three other genera, as might indeed be expected 

 from their different geographical range ; they resemble each other in 

 the peculiar arrangement of the ventral tract, which in its posterior 

 portion at the end of the sternum is composed of three rows of 

 feathers, of which the outer one, as shown in the accompanying 

 drawing (fig. 3, p. 1/5), bends outward at some distance from the 

 inner rows but approaches them before its termination. The three 

 American genera Fiaya, Saurothera, and Coccysus agree to differ 

 from the Old-World representatives of this group, in that the ventral 

 tract is double from the point of origin at the mandibular symphysis ; 

 ill Cuculus and Cacomantis the commencement of the ventral tract 

 occupies the whole, or nearly the whole, of the area lying between 

 the two mandibular rami, and is single. 



Group B includes the genera Centropus, Pyrrhocentor, Geococcyx, 

 Guira, Crotophoga, Phanicophaes (Rhinococcyx), and Eudynamis. 



Phoenicopliaes, although regarded by Nitzsch as differing in im- 

 portant particulars from Centropus and Eudynamis, does not appear 

 to me to display any such peculiarities in its pterylosis as would 

 necessitate a further division of this group ; it has been stated, how- 

 ever, that both Phoenicopliaes and Eudynamis, although agreeino- 

 with the other genera of this group in their pterylosis, resemble 

 Cuculus m possessing a tracheo-bronchial syrinx, and on this account 

 should be placed apart. 



The remaining genera of this group may be arranged in two 

 divisions : — 



(1) Crotophaga, Guira, and Geococcyx, where the ventral tract is 

 narrow at its commencement, and only occupies the median portion 

 of the intermandibular area. 



(2) Centropus and Pyrrhocentor, where the ventral tract at its 

 commencement occupies the whole of the space between the rami of 

 the mandibles. 



It will be observed that this arrangement conveniently separates 

 the New- World from the Old-World genera, though the distinction 

 is undoubtedly a very small one ; perhaps the resemblance between 

 Geoccocyx and Centropus in the matter of the syrinx should be 

 made more account of, and these genera separated from Crotophaga 

 and Guira. Recalling the structure of the syrinx in the several 

 genera, it will be apparent that group A is also distinguishable from 

 group B by means of the structure of this organ. In all the genera 

 which I have associated together in the former of these two groups, 

 the syrinx is tracheo- bronchial ; in Group B, with the exception of 

 the genera Eudynamis and Phoenicophaes, the syrinx is bronchial, 

 though by no means constructed on exactly the same type in the 

 different genera; in Crotophaga and Guira the syrinx is purely 

 bronchial, inasmuch as the anterior rings of the bronchi are com- 

 plete, and the membrana tympaniformis does not therefore extend 

 up to the last tracheal ring ; and there can be no pessulus, and the 

 tracheal rings therefore take no share in the formation of the voice- 



