HOMRAI OF THE HIMALAYA. 183 



casket being fixed to the bill, and resting posteriorly on the vertex of the 

 cranium. If therefore the upper mandible was moveable, the casket would 

 become subject to the same motion. The orbits, when compared with 

 those of most birds, are small. There is no trace of a bony septum 

 between them, but their division is effected by a membraneous partition. 



The cervical vertebrae are twelve in number. They are articulated to 

 each other by means of small eminences, which constitute real joints. 

 This provision, which is common to all birds, gives to them that peculiar 

 freedom of motion in the neck, which the whole class more or less possess. 

 In the Buceros this motion is considerably restricted, in consequence of 

 the firmness witli which the ligaments bind these vertebrae together, par- 

 ticularly the large one which passes along the proterior part of the neck, 

 and attaches itself to the spinous processes. 



There are seven dorsal vertebrae — which are articulated to each other 

 by synchondroses, or plane joints. They are all separated, but the first 

 three are so firmly connected by ligamentous structure as scarcely to 

 admit of any motion ; the remaining four are more loosely joined. 



It may here be noticed, that as the dorsal vertebrae of this bird are 

 all moveable, it becomes a matter of question whether its power of flight 

 is in any way remarkable. Except in birds which do not fly, as the 

 Ostrich, &c. it is by no means common to meet with examples, where the 

 dorsal vertebrae are all separated ; two or more of these are generally 

 found to be anchylosed at tiieir spinous processes, or the whole of this 

 part of the spinal column may be rendered fixed and immoveable, by the 

 connecting ligaments being substituted by bone, as is very generally the 

 case in birds possessing any extraordinary activity on tiie M'iug, or 

 extensive power of flight. 



