EXTERNAL ANATOMY. BILL. 
63 
serrated, for the purpose of cutting away the outer 
leaves of the heads of plants, in order to get at those 
which are the youngest and most tender. MoUini, who 
vouches for this fact, goes on to assure us that these 
birds are consequently very destructive to the farmer ; 
and we can readily suppose that a few of them would 
very soon destroy a field of Indian corn before the 
heads had burst or come to perfection. It is probable 
that the teeth of the toucan is of essential service in 
crunching and breaking the bodies of the small birds 
which it captures, and which are reduced to a shapeless 
mass before it is tossed up in the air and swallowed. 
The only example we are acquainted with of an in- 
cessorial bird having a central or raptorial tooth to its 
bill, is the Lanio of Vieillot {fig. 28. e), a bird which 
obviously belongs to the tanagers, notwithstanding this 
anomalous formation. 
(58.) VVe may now consider the bill in regard to 
its figure ; that is, its length, breadth, and direction. A 
bill is called g/iort, when its length does not equal the 
space between the nostrils and the nape of the neck 
(fig. 30. a) ; it is then said to be shorter than the head ; 
when these two parts are equal, the hill is termed mo- 
derate (h) ; but when it exceeds the length of the head, 
it is designated as long (c). Its 
circumference assumes three 
principal forms ; for it is either 
compressed, depressed, or round. 
The lengtli of a bill is usually 
estimated from that part which 
protrudes beyond the front of 
the head; and not, unless so 
expressed, from the angle of 
the mouth to the tip of the 
upper mandible. We .shall 
adopt this plan, because it is in general use, although the 
latter mode of measurement is certainly more strictly 
correct than the former. According to these views, the 
shortest billed birds become those which have the widest 
