426 



ZOOLOGY 



Gallincs. With the doves are included the pigeons. About a 

 dozen species are found in America. None of these species is 

 very numerous. A century ago the passenger pigeon occupied 

 the region east of the Mississippi River in great flocks number- 

 ing millions of individuals. In the hope of saving the species 

 there has been for some years a standing offer of consider- 

 able sums of money for information of a nesting pair of this 

 species. The domestic pigeon, in its numerous varieties, has 

 arisen by breeding and selection from the blue rock pigeon of 



FIG. 228. Gold-finch (Spinus tristis). U. S. Dept. Agriculture Year-book, 1898. 



the Old World. In cross breeding we frequently get "rever- 

 sions ' ' to this type, showing that the characters are being carried 

 in the germ plasm even when the combinations were not such as 

 to make them appear in the body. 



In this group the young are fed with food digested by the 

 parent and regurgitated into the mouth of the helpless young. 



The Pici (woodpeckers) have two toes directed forward and 

 two backward in adaptation to the position they take in climb- 

 ing. The tail may have stiff, pointed feathers with which they 



