22 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
Sub.-Fam. — BUTEONINiE. 
Craxirex. Gould. 
Rostrum JButeonis sed longius; mandibulee superioris mar go rectus; versus 
apicem subitd incurvus. Alee elongates. Cera lata. Nares fere rotundee, 
apertee. Tarsi mediocres, anticb squamis tecti. Digiti magni, fortes ; ungues 
obtusce. 
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- 
borinse, 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 Polyborinee 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- 
borinee. 
