INSESSORIAL BIRDS. 233 



such an approach to the scansorial structure that many have referred 

 the family to the order Scansores ; and I believe that it expresses 

 the fissiroatral tendency in the sub-order, not yet determined, which 

 represents the Scansores in the great order Insessores. Mr. A. R. 

 Wallace, whose opinions on these subjects always deserve attention, 

 adds the Hnmming-birds (Trochiiidse), the PufF-birds (Capitonidss), 

 which he agrees with most recent ornithologists in separating from 

 the Scansorial Bucconidse, and the Hornbills (Buerotidas). The 

 Humming-birds, in their power of flight, their feeding on the wing, 

 and their small and feeble feet, undoubtedly exhibit Fissorial charac- 

 ters, but the slender pointed beak, adapted for extracting food from 

 flowers, is most strikingly Tenuirostral, and though the one family 

 has a foot suited for moving, on branches, whilst the other relies 

 chiefly on its wings, the relationship between Promeropidse and 

 Trochiiidse is too close to be disturbed. Regarding Trochiiidse aa 

 expressing the Fissirostral tendency among Tenuirostres, we perhaps 

 avoid all real difficulty. Capitonidae had been also included among 

 the Fissirostres by Dr. G-. E. Gray^ who treated them as a sub- 

 family of Kingfishers. Mr. Wallace elevates them into a family, 

 and I must think rightly, if we grant their separation from Buc- 

 conidse ; but I have hitherto failed to appreciate the reasons for this 

 separation, excepting as sub-families of Bucconidce — the family of 

 Scansores which expresses the Fissirostral tendency. As to Bucero- 

 tidsB, their foot, though the two toes are partially united, is not 

 characteristically syndactyle, the expansion of the toes beneath al- 

 lowing of walking or hopping on branches, and there can hardly be 

 said to be any other fissirostral character. I readily admit that the 

 Hornbills have no real or close affinity with the crows, near which 

 they have been often placed, and their relations with the Toucans, 

 though striking, are more of analogy than immediate affinity. Their 

 mode of life, according to Mr. Wallace's own interesting account, is 

 far removed from that of any Fissirostral family. 



Having now decided upon the families which in my judgment can 

 be admitted as truly Fissirostral, it only remains to point out how 

 they severally express the tendencies towards the sub-orders of In- 

 sessores, or the five other admitted orders of Birds, in the centre of 

 which we suppose Insessores to be placed. Alcedinidse, the King- 

 fishers, manifestly express the Raptorial tendency ; the second, the 

 active tendency, shows itself sometimes in arboreal, sometimes ia 



Vol. IX. a 



