xliv Trans. Acad. Sci. of St. Louis. 



of the Radiata." Of the 425 titles listed in the bibliography 

 appended to Marcou's biography, 274, including seven posthu- 

 mous publications, represent work done in America. 



From his student days, Agassiz was deeply impressed with the 

 importance, to the naturalist, of the opportunities afforded by 

 well-equipped scientific expeditions. Disappointed in an early 

 ambition to accompany Humboldt on his tour of exploration in 

 Asiatic Russia (1829), and again in the hope awakened by 

 Cuvier (1832) of receiving aid from funds at the disposal of the 

 Museum of Natural History, his field work in Europe was limited 

 to excursions in the Alps and within a restricted area in Switzer- 

 land and Germany, and to the study of the evidences of glacial 

 action in the British Isles. In America, through the courtesy of 

 Superintendents Alexander D. Bache and Benjamin Peirce, he 

 was enabled to make frequent trips on the vessels of the United 

 States Coast Survey along the Atlantic coast, including a scientific 

 survey of the Florida reefs and dredging on the Bahama Banks. 

 The voyage of the new surveying steamer '^Hassler" (December 

 4, 1871, to August 24, 1872), from Boston to San Francisco, 

 was utilized as a distinctively scientific expedition, under his 

 direction. In 1865-66 he conducted extended explorations in 

 Brazil. He had planned to spend several months, in much 

 needed rest from work, at Rio de Janeiro. His friend, Mr. 

 Nathaniel Thayer, learning of his purpose, offered to defray the 

 expenses of six assistants; the Pacific Mail Steamship Company 

 tendered a free passage to Rio, for the entire party; the Secretary 

 of the Navy instructed the officers of its vessels stationed along 

 the coast ''to give aid and support''; the Brazilian Steamship 

 Company placed a special steamer at his disposal for the ascent 

 of the Amazon from Para to its confluence with the Rio Negro; 

 and the Emperor, Dom Pedro II, besides proffering ''every 

 possible attention and mark of good- will," detailed a small war 

 steamer for the navigation of the great tributary rivers. The 

 expedition occupied sixteen months, of which ten months were 

 spent on the Amazon, as far as the borders of Peru. 



Agassiz's field explorations in the United States extended 

 from Maine to Wyoming. His lecturing trips and longer j ourney s 

 afforded large opportunities for observing and collecting, which 

 he utilized to the utmost. His practised vision detected the 

 tracks'of ancient glaciers and vestiges of .a great post-tertiary ice 

 sheet in regions where their existence had previously been 

 unsuspected. Rivers and lakes, and the markets of the towns 



