BATS 43 



pelled to travel on their bellies, they do neverthe- 

 less return year after year to the old laying-up 

 places. The question of a seasonal movement in 

 bats, similar to migration in birds, greatly exercised 

 my young mind in former years in a country where 

 bats had no business to be. This was the level, 

 grassy, practically treeless immensity of the pampas, 

 where there were no hollow trunks, nor caves and 

 holes for bats to shelter in, nor ruins and buildings 

 of brick and stone which would be a substitute for 

 natural caverns. Human dwellings were mostly 

 mud and straw hovels, and the only trees were those 

 planted by man, and were not large and could not 

 grow old. The violent winds swept this floor of the 

 world, which was unsheltered like the sea. Yet 

 punctually in spring the bats appeared along with 

 the later bird migrants, and were common until 

 April, when they vanished, and then for six months 

 no bat would be seen in or out of doors. Clearly, 

 then, they were strictly migratory, able like birds 

 to travel hundreds of miles and to distribute them- 

 selves over a vast area. They were, in fact, both 

 migrants and hibernators, since we cannot but 

 suppose that they forsook the pampas only to find 

 some distant place where they could pass their 

 inactive period in safety. 



At one point, about two hundred miles south 

 of Buenos Ayres city, the level pampa is broken by 

 a range of stony hills, or sierras, standing above 

 the flat earth like precipitous cliffs that face the 

 sea. On my first visit to that spot I travelled 



