BUCEHOTES i>19 



adductor, though the direction of this tendon is somewhat 

 different from what is found in Aceros. 



The skull is doubly desmognathous. There are distinct 

 basipterygoid processes, large in B. rhinoceros, almost va- 

 nished in A.nipalensis, with which, however, the pterygoids 

 do not articulate. The interorbital septum is widely fenes- 

 trate. The fused lacrymals and ectethmoids together make 

 a large plate of bone ; the postfrontal processes are large. 

 The atlas is fused with the axis. The haemapophyses are 

 slight. There are fourteen or fifteen cervical vertebrcc ; they 

 are median in C12-D2. C14 and Dl have a median and 

 two lateral processes. 1 The sternum, which is faintly two- 

 or four-notched, has both spin a externa and interna. 



The liver lobes present some differences in different 

 horiibills. 



Commencing with Bucorvus abyssinicus, in which the 

 right lobe is larger than the left, the series terminates with 

 Buceros coronatus, in which the left lobe is larger than the 

 right. The following table shows the relations of the liver 

 lobes in such hornbills as have been examined : 



Bucorvus abyssinicus. R>L. 



Aceros nipnlensis. R > L. 



Bnceros bicornis. 

 Sphagolobus atratits. 

 Bycanistes subcylindricus. 

 Buceros plicatus. 

 Buceros rhinoceros. 

 Buceros coronatus. 



R>L. 

 R>L. 

 R>L. 

 R = L. 

 R = L. 

 R<L. 



I have noticed a peculiarity in several species of horn- 

 bills which is not found in all other birds. In all birds the 

 two lobes of the liver are completely separated from each 

 other by the umbilical ligament, which bears the umbilical 

 vein (this appeared to be particularly large and well deve- 

 loped in all hornbills which have been dissected by me) ; and 

 in addition one liver lobe the right- -is commonly separated 

 from the abdomen by a thin membranous septum. In horn- 

 bills both lobes of the liver are thus shut off ; I have figured 



1 In Dichoceros bicornis there is a tendency towards the formation of a 

 hypapophysial canal. 



