584 



ON A NEW HOENBILL. 



[1878. 



P.Z.S.1878, On a new Species of the Genus Buceros. By Arthur, Marquis of Tweeddale, F.E.S., President 

 P' ' ■ of the Society. [' From the Proceedings of the Zoological Society of London,' read 



February 19, 1878.] 



In a collection of birds made at Amparo (in the extreme south of the Philippine island of Leyte), 

 and sent to me by Mr. Everett, are some examples of a Hombill of the genus Buceros, which 

 differ from the two other known Philippine species * sufficiently to require description. The 

 characters which differentiate the large Buceros of Mindanao, B. mindanensis, from the one 

 which inhabits Luzon were stated some months ago before this Society (see P. Z. S. 1877, p. 543) f. 

 But in those two species the form and general contour of the bill and casque are alike, whereas 

 in this second representative form of B. hydrocorax the form of the casque is very different. 

 The colouring of the bill represents that of B. mindanensis ; and in 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 flat but arched along 

 its length, the crown of the arch during the course of its anterior half forming an almost acute 



P.Z.S.1878, 

 p. 278. 



Fig. 1. 



^ 



Side view of head of Buceros mindanensis. 

 Fig. 2. 



ridge 



Head of Buceros mindanensis, from above. 



In the 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 



* B. hydrocorax and B. mindanensis. t [_Antea, p. 467.— Ei>.] 



