276 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1934 



THE BUTTERFLIES OF THE EXTREME SOUTH 



In the Antarctic regions the conditions are quite different from 

 the conditions that are found in the northern part of the Northern 

 Hemisphere. Here lies the great continent of Antarctica, which is 

 too cold to support plants and is thus wholly devoid of insect life. 

 More or less remote from this are various Antarctic and sub-Antarctic 

 islands, on none of which do butterflies exist. 



The only continent that extends far enough southward to enter 

 a region in any way comparable to the northern regions of the 

 Northern Hemisphere is South America. But the climate of south- 

 ern South America is wholly different from that of the northern 

 portions of Europe, America, or Asia. Southern South America 

 is so narrow that its climate is more like the climate of an island 

 than it is like the climate of a continent. 



Across the Magellan Strait from the southern extremity of con- 

 tinental South America lies the archipelago called " Tierra del 

 Fuego." The eastern portion of this archipelago consists of the 

 island called King Charles' South Land, an island very much larger 

 than all the rest of the archipelago together, being considerably 

 more than 200 miles in length from north to south. It forms a 

 southern extension of the Patagonian pampas, which it much re- 

 sembles in its physical constitution, and in its fauna and flora. The 

 low-lying, flat, or slightly rolling plains are covered with a rich 

 growth of tall herbage. In the south a long peninsula projects west- 

 ward to the Pacific. This becomes rough and mountainous, with 

 two peaks rising to nearly 7,000 feet — a true alpine region with 

 numerous snow-clad summits and glaciers reaching to the sea. 



The western and southern portions of the archipelago are essen- 

 tially mountain regions, resembling the western extension of King 

 Charles' South Land. They are extremely rough and rugged, with 

 a much moister climate than the larger eastern island, and are 

 densely forested, the forests consisting chiefly of an evergreen beech, 

 and the glossy-leaved evergreen winter-bark. Above the forests, 

 which rise to between 1,000 and 1,200 feet, there is a zone of peaty 

 soil with stunted alpine plants that reaches as far as the snow line — 

 that is, as high as from 3,000 to 3,500 feet. In this rough and 

 forbidding land the winters are mild, with an average temperature 

 of 32° for July, and the summers are cool, with an average of 50° 

 for January, the warmest month. The mean temperature for the 

 year is 42°. But throughout the year fogs, mists, rains, snows, and 

 high winds prevail, and there are frequent and sudden changes from 

 fair to foul weather. 



Tierra del Fuego is the same distance south of the Equator that 

 the Aleutian Islands are to the north of it, and the temperatures 



