BUOEROTES 216 



BUCEROTES 



, — Oil gland tufted. Muscle formula, AXY. Cseoa absent.. 

 Skull desmognatlious. 



The well-marked family Bueerotidae contains at least two 

 distinct genera, Buceros and Bucorvus. The latter (the 

 ground hornbill) is entirely African ; the former, which has 

 been much subdivided, is both African and Asiatic. 



The great casque,^ not always equally developed, and the 

 long bill, frequently serrated along its margins, and the 

 largely black and white or black plumage distinguish these 

 birds. But the small Toccus is a less typical form. The 

 syndactyle foot, in which the second and fourth toes are 

 united to the third— the latter for several joints, the former 

 for only one — is highly distinctive, and is repeated in the 

 ground-living Bucorvus. 



The oil gland is tufted. The feathers have no aftershaft. 

 There are ten rectriees. 



The pterylosisoi Bucorvus abyssmicus has been described 

 and figured by Nitzsch. 



The neck is completely feathered, except at its lower end, 

 both dorsally and ventrally. The former is the commence- 

 ment of the very narrow dorsal space of a long oval form, 

 but not extensive. The pectoral tracks diverge at end of 

 neck, but are subsequently undivided. 



The carotids are double in Bucorvus ; the left only is 

 present in others. The remarkable obliteration of the 

 carotids in the former genus, and their replacement by a pair 

 superficial in position, have been described by Gabeod ^ and 

 Ottley.^* 



The tensores patagii are in some ways characteristic of 

 the Bucerotidse. In Buceros convexus (cf. Fubbbingee) 



' Owen, ' On the Anatomy of the Concave Hornbill,' P. Z. S. 1833, p. 102. 



" ' On a Peculiarity in the Carotid Arteries ... of the Ground Hornbill, 

 P. Z. S. 1876, p. 60. 



" ' A Description of the Vessels of the Head and Neck in the Ground Horn- 

 bill,' ibid. 1879, p. 461. 



