408 NATURAL HISTORY OF BIRDS. 



the male bring anything but food ; and I never found any food which had been 

 rejected under the tree, and but very little ordure, which latter had apparently been 

 thrown out by the female when the closing-work was finished. The male bird would 

 alight near, then fly to the hole, holding on to the bark by his claws, and knock with 

 his beak. On this the points of that of the female appeared, and received the fruit, 

 when the male flew off. The hole was at first, perhaps, six inches in height, and three 

 or four wide. When closed up, the opening at the widest part was a little larger than 

 would admit the finger. It should, however, be borne in mind that the bill opened 

 upwards, and thus had three or four inches play. The plastering operation took two 

 or three days, after which the ordure was thrown out." 



We might continue with similar testimony from Wallace, Bernstein, and other 

 travelers, but want of space prevents us from quoting more, inasmuch as the above 

 will suffice to give an idea of one of the most extraordinary nesting habits we know 

 of. We do not wonder that the hornbills play a great role in the imagination of the 

 natives, and find it quite natural that the female hornbill is regarded by the Burmese 

 as a model of virtue. 



The hornbills vary in size from that of a raven to that of a jay ; and there is an 

 endless variation of the casque from a nearly obsolete ridge to the immense upturned 

 horn of the rhinoceros bird. A somewhat more aberrant form is Rhinoplax vigil, 

 which has a solid, not cellular, casque, bare neck, and elongated central tail-feathers. 

 It lives in the Malay peninsula, Sumatra, and Borneo. 



There seems to be good reasons for regarding the ground-hornbills, three African 

 species, one of which is illustrated in our cut, as constituting a special sub-family. 

 Their casque is hollow, and open in front in the species figured ; the tarsi are long 

 and the tail comparatively short. There are also important internal differences from 

 the other hornbills, for, while these have a muscular formula of AXY, the ground 

 hornbills have only XY. The difference in the external structure of the feet and in 

 the myological formula is concomitant with a peculiarity in the movements of these 

 birds, as the tree-hornbills hop with both feet together, while the ground-hornbills 

 (Bucorvinse) walk, placing one foot in front of the other. A unique anatomical 

 feature has been described by Mr. W. Ottley. Some of the tree-hornbills have two 

 carotids, others have one ; but JBucorvus has no functional carotid at all. The 

 vessels are only represented by two imperforate fibrous chords, and their function 

 is performed by the greatly enlarged representatives of the comes nervi vagi. 

 Hence, the origin of the arteries for the supply of the head also differs from the 

 usual arrangement, a superior thyroid artery and a facial artery being both absent. 

 As might be expected, the habits of the ground-hornbills are different from those 

 of their tree-loving relatives. They move with ease over the ground, on which they 

 spend much of their time, feeding upon insects, reptiles, and occasionally small 

 mammals. 



Few birds can better illustrate the necessity of taking into account all the char- 

 acters in determining the place in the system than those composing the present super- 

 family, the UPUPOIDE^E. If we only knew their skin, the posterior part of their 

 breastbone, their deep plantar tendons and carotids, we should most certainly refer the 

 hoopoes to the Passeres; but since, also, all the other points of their external and 

 internal anatomy are well known, there is no room for doubt but that they form an 

 isolated group belonging to the Picarian order, the nearest allies being probably the 

 hornbills, as already mentioned. Still, as they are yet classed with the larks or with 



