22 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



Sub.-Fam.— BUTEONINiE. 

 Craxirex. Gould. 

 Rostrum Suteonis sed lotigms; mandibulce siiperioris margo rectus; versus 

 apicem subitd incurvus. Ales elongate. Cera lata. Nares ferk rotundce, 

 apertce. Tarsi mediocres, antici squamis tecti. Digiti magni, fortes; ungues 

 ohtusce. 



Mr. Gould was partly led to institute this genus from the facts communicated 

 to him by me regarding the habits of the following species, which is found in the 

 Galapagos Archipelago, and there supplies the place of the Polybori and Mil- 

 vagines of the neighbouring continent of America. If a principle of classification 

 founded on habits alone, were admissible, this bird, as will presently be shown, 

 undoubtedly would be ranked with more propriety in the sub-family of Poly- 

 borinae, than amongst the Buzzards. To the latter it is closely related in the 

 form of its nostrils; in the kind of plumage which covers the head, breast, and 

 shoulders ; in the reticulation of the scales on its feet and tarsi, and less closely 

 in the form of its beak. To the Polyborinae it manifests an affinity in the great 

 strength and length of its toes and claws, and in the bluntness of the latter ; 

 in the nakedness of the cere, in the perfectly uncovered nostrils, in the pro- 

 longation and bulk of the bill, in the straightness of the line of commissure, and 

 in the narrow shape of the head. In these several respects, taken conjointly with 

 its habits, this bird supplies a most interesting link in the chain of affinities, by 

 which the true buzzards pass into the great American sub-family of carrion- 

 feeding hawks. I am, indeed, unable to decide, whether I have judged rightly 

 in placing this genus, as first of the Buteoninse, instead of last of the Poly- 

 borinae. 



