PLANTAIN-EATERS, HORNBILLS. 107 



being that suggested by Mr. Bates, that it simply 

 enables them to reach fruit at the ends of slender twigs 

 which, owing to their weight and clumsiness, they would 

 otherwise be unable to obtain. At first sight it appears 

 very improbable that so large and remarkable an organ 

 should have been developed for such a purpose ; but 

 we have only to suppose that the original toucans had 

 rather large and thick bills, not unlike those of the 

 barbets (to which group they are undoubtedly allied), 

 and that as they increased in size and required more 

 food, only those could obtain a sufficiency whose un- 

 usually large beaks enabled them to reach furthest. So 

 large and broad a bill as they now possess would not 

 be required ; but the development of the bill naturally 

 went on as it had begun, and, so that it was light and 

 handy, the large size was no disadvantage if length 

 was obtained. The plantain-eaters of Africa are less 

 remarkable birds, though adorned with rich colours and 

 elegant crests. The hornbills, though less beautiful 

 than the toucans, are more curious, from the strange 

 forms of their huge bills, which are often adorned with 

 ridges, knobs, or recurved horns. They are bulky and 

 heavy birds, and during flight beat the air with pro- 

 digious force, producing a rushing sound very like the 

 puff of a locomotive, and which can sometimes be 

 heard a mile off. They mostly feed on fruits ; and as 

 their very short legs render them even less active than 

 the toucans, the same explanation may be given of the 

 large size of their bills, although it will not account for 

 the curious horns and processes from which they derive 

 their distinctive name. The largest hornbills are more 

 than four feet long, and their laboured noisy flight and 



