20 



EXTERNAL PARTS 



hrane ' extending over the nostrils, is found in the doves and 

 in the pigeons. The rictal portion of the mouth is frequently 

 fringed Avith longer or shorter hairs; these are called rictal 

 brisfles.'- 



Shape of the gape. — The gai)e is straiyht^ when the commis- 

 sural line, formed by the tomia and the rictus, is straight. 

 This line may ho rurrcdr sinuate,* or augulate.'' 



General size and form of the bill. — The length of the head is 

 used to measure the length of the bill. A long "^ bill is longer 

 than the head, a short' bill shorter, and one of medium length 

 is about as long as the head. A compressed^ bill is one flat- 

 tened sideways, so that its height is greater than its width. A 

 depressed ' one is flattened up and down, or is wider than high. 

 A straight ^*^ bill is not only straight throughout its length, but 

 is also in line with the head. If not in line with the head, it 

 is said to be hent}^ A recurved '-' bill is one that curves ui)ward, 

 and a clecurved '^ bill one that curves downward. A bill may 

 be decurved throughout, or it may have merely a decurced tip.^* 



The usual bill is sharp-pointed at the end and is called 

 acute.^ If it has an abrupt and somewhat rounded end, it is 

 obtuse.^'^ Acuminate^' indicates not only an acute end, but a 

 slender bill as well. If very slender and sharp, it is called at- 

 tenuate.^^ In some cases, as among the hummingbirds, still 

 more emphatic words are needed to denote slenderness and 

 sharpness. Subulate^^ is more emphatic than attenuate, and 

 acicidar indicates the extreme limit in this direction. 



