Fig. 40. Dichoceros bicornis and nest. 



Suborder BUCEROTES. 



Caeca wanting; oil-gland tufted. Sternum with two shallow 

 notches, one on each side in the posterior margin ; behind the 

 ill-developed manubrium is a perforation as in Meropidce. Both 

 carotids present as a rule, though there are . exceptions. Spinal 

 feather-tract not defined on the neck, which has no lateral bare 

 tracts or apteria ; no aftershaft ; no down on bare parts of skin. 

 Deep plantar tendons as in Coracice. 



Family BUCEROTIIXE. 



An enormous bill, generally curved, and furnished in most 

 genera with a casque upon the basal portion of the culmen ; this 

 casque varies in shape, and is generally hollow or cellular, but the 

 anterior part is solid in RTiinoplax. Primaries 11. Tail-feathers 

 10. The under wing-coverts as a rule do not cover the basal part 

 of the quills, and this may, as Mr. Ogilvie Grant has suggested, 

 account for the extraordinary noise made by some of the larger 

 forms when flying, the sound being produced by the air rushing 

 between the quills. The eyelids are furnished with strong eye- 



