34 FORM AND HABIT: THE BILL. 



that of the female is long and curvecf. The birds feed 

 on larvae, which they find in dead wood. The male 

 hammers and chisels away the wood very much as Wood- 

 peckers do, while the female uses her bill as a probe. 

 We have, therefore, the singular case of two forms of 

 the bill arising in the same species as a result of or caus- 

 ing a corresponding difference in habit. 



