278 THE MARQUIS OFTWEEDDALE ON A NEW HORNBILL. [Feb. 19, 



the general colouring of the plumage there is little or no difference. 

 It is the form of the casque that provides the differential specific 

 character. Instead of being produced forward as in B. hydrocorax 

 and B. mindanensis, with an abrupt, compressed, and elevated 

 anterior margin, the superior plane of the casque loses itself and 

 dies away on the culmen. The superior plane of the casque is not 

 fiat but arched along its length, the crown of the arch during the 

 course of its anterior half forming an almost acute ridge. In the 



Fig. 1. 



Side view cf bead of Bueeros mindanensis. 

 Fia. 2. 



Head of Bueeros mindanensis, from above. 



two known species the contour of the superior flat plane of the 

 casque is that of an oval, the posterior end being rounded and the 

 anterior pointed. In this Leyte species the posterior end is also 

 rounded ; but the sides, instead of gradually expanding to the greatest 

 breadth of the superficial area and then gradually contracting to the 

 apical point, continue in almost parallel lines for about two thirds of 

 the length of the major axis of the casque, and then terminate ab- 

 ruptly, forming corners from which the sides of the remainder of the 

 casque recede until they reach the culmen. 



[S. Leyte, tf (adult), September. Iris light yellow ; orbital skin 

 darkest sepia, almost black ; gular skin dark Indian-yellow ; feet 

 coral-red ; nails dark brown-grey. — Everett.^ 



