14 WHITE-BEAKED HORNBILt. 



its curvature, measures four inches and three Iines> 

 and the thickness of both mandibles, taken toge- 

 ther, is about eighteen lines: they are nearly equal, 

 irregularly toothed on their edges, and end in ob- 

 tuse points : the casque or process occupies nearly 

 two thirds of the length of the bill, covering the 

 front, to v^hich it adheres : it is truncated in front, 

 v^here it terminates in a thin edge, swelling gra- 

 dually upwards on the sides, the ridge or upper 

 part forming a more elevated arc of a circle in the 

 middle: it is terminated behind by a large rounded 

 point, black above and round its border: in front 

 is also a black patch, which descends a little on the 

 upper mandible, which is edged at its base by an 

 irregular black band of only two lines in width: 

 the lower mandible is bordered on each side its 

 base by a much broader black band, which termi- 

 nates in a point beneath the bill : both mandibles 

 are also edged with black along the serrated part, 

 and, as well as the mouth, are black internally; 

 while externally both the bill and casque are of an 

 ivory whiteness. After this description of the bird 

 we might readily suppose it a mere variety of the 

 Unicorn Hornbill; but, on a careful comparison of 

 the two birds, I am convinced that they are distinct 

 species, notwithstanding this similarity. In the 

 Unicorn Hornbill the casque is flattened and fur- 

 rowed on its sides, and terminates behind in a 

 living skin. In the present bird on the contrary 

 it is smooth, swelled on the sides, exceeding in its 

 middle part the diameter of the mandibles, and is 

 closed behind by a horny substance similar to that 



