1901.] SHUFELDT — OSTEOLOGY OF THE CUCKOOS. 47 



my previous memoirs, and they are to a greater or less extent struc- 

 turally linked to a variety of other families of birds that have long 

 puzzled both the ornithologist and the avian anatomist. By their 

 zygodactyle feet they may at once be distinguished from any of the 

 enormous group of the Passer -es, to be considered later on. (The 

 MSS. at this writing are complete.) 



Their affinities, if there be any, with the Caprimulgi, the Cypseli, 

 the Trogones, the Troc/i Hi and the Picimust also be quite remote. 

 But this will not apply to the Kingfishers, and much less to certain 

 other groups in various parts of the Old and New World, as the 

 Musophagidcz, Btuconidce, Galbulidce, Meropidce, Momotidce, Bucero- 

 tidce, Upupidce, Todidce, Cotacidts, Bhamphastidce, Capitonidce and 

 perhaps some few others. 



These several families seem to have a Cuckoo vein running all 

 through them, strongly impressed in some cases, barely discernible 

 in others. Indeed, these groups of birds seem to have arisen from 

 some very ancient and once common stock, but by the extinction 

 of numerous related types and groups of types that once filled the 

 now many and various gaps among them, it has left in recent times 

 the most puzzling collection of polymorphic forms that the syste- 

 matist has to deal with throughout the entire range of ornithology. 

 They have become diversified through all the factors that organic 

 evolution brings to bear upon such plastic organizations as they 

 represent. 



In the opinion of a number of authoritative ornithotomists the 

 nearest affines of the Cuculidce are to be seen in the Musop/iagidce. 

 while the Meropidce are also said to exhibit especially a number of 

 cuculine affinities. Personally, I have never examined the skeleton 

 in any of the Musophagidce ; but of certain Meropidce we shall 

 speak a little further along in another memoir now in preparation. 

 One thing must be constantly borne in mind, and that is Cuckoos 

 differ not a little in their osteology among themselves — take Croto- 

 phaga and Geococcyx calif ornianas for instance — so that we meet with 

 certain species of them that in their skeletons offer a greater number 

 of characters that agree with the corresponding characters in 

 forms of other groups than do others of this suborder. Apart 

 from the Alcyones, we have in our United States avifauna no 

 very near affines of the Coccyges. 



Probably the weight of opinion would be thrown in favor of 

 placing the Cuculidce near the Musophagida, the Plantain-eaters 



