CLOSE OF THE BRAZILIAN JOURNEY. 633 



and smoothed every difficulty in the path. On 

 starting he had set before himself two sub- 

 jects of inquiry. These were, first, the fresh- 

 water fauna of Brazil, of the greater interest 

 to him, because of the work on the Brazilian 

 Fishes, with which his scientific career had 

 opened ; and second, her glacial history, for he 

 believed that even these latitudes must have 

 been, to a greater or less degree, included in 

 the ice-period. The first three months spent 

 in Rio de Janeiro and its environs gave him 

 the key to phenomena connected with both 

 these subjects, and he followed them from 

 there to the head-waters of the Amazons, as 

 an Indian follows a trail. The distribution 

 of life in the rivers and lakes of Brazil, the 

 immense number of species and their local 

 circumscription, as distinct faunae in definite 

 areas of the same water-basin, amazed him ; 

 while the character of the soil and other geo- 

 logical features confirmed him in his precon- 

 ceived belief that the glacial period could not 

 have been less than cosmic in its influence. 

 He was satisfied that the tropical, as well as 

 the temperate and arctic regions, had been, 

 although in a less degree, fashioned by ice. 



Just before leaving the United States he 

 received a letter of friendly farewell from 



