144 ELEMENTS OF ORNITHOLOGY. 
the Hummine-bird) may be called “ tenuirostral.”* If there 
is a notch or tooth-like process at the side, then such a bill is 
said to be dentirostral. A bill which is bent up towards the 
end, as in the Avocet, is termed recurved, while the opposite 
condition is decurved, as in the Curlew. In one genus of crook- 
billed Plovers of New Zealand (Anarhynchus), the bill is, as 
before said t, bent laterally. 
Before noting the terminology used to denote the parts and 
condition of either mandible, a few words may be said as to 
the covering of the bill, which will especially relate to the 
maxilla. In the immense majority of instances the bill is 
entirely hard and horny, and the investment of either jaws 
in one piece. In some Birds, however, as in the Petrels ¢, it 
may be in several pieces, and these may be moulted like the 
feathers, so that they form part of the summer dress, and con- 
stitute a secondary sexual character, as is the case in the 
Puffins §. Such bills are said to be deciduous or caducous. 
The bills of Birds are often marked with ridges proceeding 
in this or that direction, and such are called carinate or striate, 
if the ridges are pretty straight. A bill, on the contrary, is 
said to be rugose or corrugated if the prominences form rather 
irregular wrinkles than ridges. If the bill is marked with 
linear depressions instead of “ridges, it is termed “ sulcate,” each 
groove being a sulcus or furrow. If the depressions are not 
elongated, but are little rounded ones or pits, the bill is called 
punctate. 
Instead of being all hard as horn, a bill may be of rather 
leathery texture, as in the Ducks, or invested with a sort of 
skin and yery sensitive towards the tip, as in the Woodcock. 
The bill may be hard towards the tip, but notably softer at the 
base, as in that in most Pigeons and Plovers. In Parrots and 
Hawks the base of the bill is clothed by a peculiar wax-like 
investment called a cere, and this sometimes bears feathers. 
Sometimes the bill bears very large, soft, fleshy processes, and 
then it is said to be carunculate. If the processes are smaller, 
like warts, the bill is termed papillose, the warts bemg named 
papille. 
Not only is the lower jaw moveable, but the upper one is so in 
a slight degree, though this is hardly noticeable, save in Parrots, 
ee ante, p. 100. | See ante, p. 58. 
* Se 
t See ante, p. 31. § See ante, p. 25. 
