viil CONTENTS 



XIII. WHY DO ANIMALS BECOME EXTINCT? 



Extinction sometimes evolution, 175; over-specialization as a cause 

 for extinction, 176; extinction sometimes unaccountable, 176; 

 man's capability for harm small in the past, 177; old theories of 

 great convulsions, 178; changes in nature slow, 178; the case of 

 Lingula, 180; local extermination, 180; the Moas and the Great 

 Auk, 182; the case of large animals, 183; interdependence of living 

 beings, 184; coyotes and fruit, 184; Shaler on the Miocene flora 

 of Europe, 185; man's desire for knowledge, 186. 



XIV. A RETROSPECT; DISCOVERIES OF THE PAST 

 TWENTY YEARS 



Ancestors of the Elephants and Manatees, Dinosaurs, 187; Anky- 

 losaurus, an animated citadel, 187; Tyrannosaurus, the most 

 formidable beast of prey, 188; Brachiosaurus, the tallest reptile, 

 188; the Asphalt Trap of La Brea, 188; geography of the past, 

 189; references, 191. 



INDEX 195 



