GENERAL FEATURES OF BUTTERFLY LIFE 



§ I. The West Coast. 



In this book the West Coast is considered as including all lands 

 west of the continental divide, the waters of which more or less 

 directly flow into the Pacific Ocean. This region is so extensive 

 that in square miles it might well be considered an empire in 

 itself. As delineated on the map it covers nearly as much surface 

 as that part of the United States east of the Mississippi River, or 

 about 1,100,000 square miles; whereas, to the eye of the lepidop- 

 terist it is vastly larger, as the wide expanse in latitude, the influ- 

 ences of the ranges of high mountains, and of the arid interior 

 desert region, all combine, each in its own peculiar way, to give 

 variety and a larger number of species to relatively smaller ter- 

 ritory. 



The Great Basin of Nevada, Utah, and Wyoming, is as yet 

 comparatively unknown ; this interior region is rather scantily 

 represented in this work, because, as just stated, it is a new coun- 

 try, and has not yet been explored ; but many new and striking 

 forms of desert life will be found there as soon as the butterfly 

 man's net begins to wave over that wide-spreading, sandy land. 

 But as the peculiar climate and desert environment is general, 

 over the whole region, the fauna will also be found to be less 

 broad and less varied than that of the more immediate coast 

 region, of high mountains and fertile valleys, and a more varied 

 flora. 



§ 2. Distribution by Altitude. 



Increased altitude, as on mountains, has the same effect on the 

 ornamentation of butterflies as a more northern latitude. A 

 species which occupies both valleys and mountain heights will be 

 found to be darker in color in those examples from the mountains 

 than those living in the lower valleys. Take Meganostoma 



