HORNBILL 435 
of it until 1801, when Latham described the plumage from a 
specimen in the British Museum, and the first figure of the whole 
bird, from an example in the Museum at Calcutta, was published 
by Hardwicke in 1823 (Trans. Linn. Soc. xiv. pl. 23). Yet over 
twenty years eiapsed before French naturalists had seen more 
than its head. Under Rhinoplax Sundevall places the Buceros 
comatus of Raffles; but this would seem to be a wrong position for 
that species, the type of Bonaparte’s genus Berenicornis, since it does 
not appear to possess a frontlet of solid horn, and Mr. Elliot puts 
it in the genus Anorrhinus. 
Of other forms of Hornbill there is not room here to treat at 
length. In some, as the Indian Anthracoceros and the Ethiopian 
Bycanistes, the epithema grows out in such wise as to make the 
bird seem as if it had two beaks, one superimposed upon the other. 
Great as is the wonder which this arouses among stay-at-home 
ornithologists, it has failed, as in other cases, to excite enough 
curiosity among those that have opportunities of observation to 
enable them to provide the least hint as to the use it serves in the 
bird’s economy. In other forms the epithema is hardly developed, 
and indeed a fairly complete series may be traced from (setting 
aside Bucorvus) Buceros to certain species of Z'occus in which it may 
be said not to appear. In some of the intermediate forms it is 
curiously corrugated, and the ridge and furrow surface extends in 
Cranorrhinus to the mandible. The development, however, of this 
most characteristic feature of the Family depends in some species, 
as might be expected, more or less on age and sex; and, important 
as it undoubtedly is, too much weight should not be assigned to it 
or other means of diagnosis neglected on its account. That excel- 
lent observer Tickell in his manuscript Birds of India (in the library 
of the Zoological Society of London) divides the Hornbills of that 
country into two genera only, Buceros and Aceros, remarking that 
the birds of the former fly by alternately flapping their wings and 
sailing, while those of the latter fly by regular flapping only.1 
Several differences of structure are presented by the sternal 
apparatus of the various Bucerotidy, and it is quite possible that 
these differences may be correlated with Tickell’s observations so as 
to furnish, when more is known about these birds, a better mode of 
classing them, and the same may be said of those of the African 
group containing the genus Toccus and its allies. 
As a whole the Hornbills, of which more than 60 species have 
been described, form a very natural and in some respects an isolated 
group, placed by Prof. Huxley among his Coccygomorphe. It has 
1 The noise made by the wings of some of the large species in their flight is 
compared by Mr. Wallace, in an admirable article on the Family (Jnéellectual 
Observer, 1863, pp. 310 et segg.), to the puffing of a locomotive steam-engine when 
starting with a train, and can be heard a mile off. 
