XU CALIFORNIA ACADEMY OP SCIENCES. 



THE DIRECT INFLUENCES OF THE ENVIRONMENT 225 



Beddard on the general effects of food on color, 226; Stejneger's 

 theory of melanism and albinism, 226; Sauermann's experiments 

 in changing color by food, 227; influence of temperature, moist- 

 ure and sunlight on food, 229; instances where intensifying and 

 bleaching has been the result of the presence or absence of sun- 

 light, 230; Garman on the bleaching power of sunlight, 231; ob- 

 jections to Garman's theory, 231; pale colors of the under parts 

 of animals due to the absence of sunlight, 232; reconciliation 

 of this Tiew with the bleaching effect of sunlight, 233. 



GEOGRAPHICAL DISTRIBUTION AS A FACTOR IN THE 



EVOLUTION OF COLORS 234 



General survey of the f aunal areas of North America, in their relation 

 to extralimital faunas, 234; birds of the Boreal area, 235; absence 

 of brilliantly colored genera among boreal forms, 236; reasons for 

 this lack of specialization among northern forms, 237; brilliancy 

 of tropical species, 238; Beddard on special relations of color to 

 geographical distribution, 238; on the resemblance of the colors 

 of Sturnella and Macronyx, 239; Ridgway on the relation between 

 color and geographical distribution, 241; Spinus psallria as an 

 instance of melanism as related to distribution, 241; other ex- 

 amples of melanism toward the south, 243; intensification in 

 yellow toward the tropics, 243; intensification of red with change 

 in climate, 244; increase in blue from north to south, 245; Cyano- 

 citta stelleri studied with reference to the connection between 

 color marks and geographical distribution, 245; J. A. Allen on the 

 relation between climate and geographical races, 247; Melospiza 

 fasciaia as an instance of the result of climatic influence, 248; the 

 ice age as a factor in isolation, 249; examples of forms produced 

 by an east and west isolation, 250; examples of north and south 

 isolation, 252; varieties or closely related species whose ranges 

 overlap, 253; particular instances where the different races cannot 

 have been produced solely by climatic influences, 255; Myiarchus 

 as an example of species which have been produced by climatic 

 influences alone, 256. 



ORDERS, FAMILIES, AND GENERA OF NORTH AMERICAN 

 BIRDS, CONSIDERED FROM THE STANDPOINT OF THEIR 



EVGLUTION 257 



BIBLIOGRAPHY 337 



EXPLANATION OF PLATES 345 



INDEX , 349 



