38 Journal of Travel and Natural History 



course of the rivers San Francisco, Paranaliyba, and Tocantins, 

 besides making shorter excursions up the affluents of the Amazons. 



The principal scientific topics discussed in the book, relate to 

 the distribution of the Amazonian fishes, the discovery of immense 

 deposits, believed to be drift, and the physical history of the Great 

 River. 



Mr Agassiz believes that several well-characterized ichthyological 

 faunae can be distinguished in the Amazons. " The species," he 

 says, " inhabiting the river of Para, from the border of the sea to 

 the mouth of the Tocantins, differ from those which are met in the 

 network of anastomosis which unite the river of Para with the 

 Amazons proper. The species of the Amazons below the Xingu 

 differ from those which occur higher up ; those of the lower course 

 of the Xingu differ from those of the lower course of the Tapajos. 

 Those of the numerous igarapes and lakes of Manhaes differ as 

 much from those of the principal course of the Great River and of 

 its great affluents." Even shores, which, from a geographical point 

 of view, must be considered as opposite banks of the same stream, 

 were found to be the abodes each of an essentially different 

 ichthyological population. A few. fish, such as the Pirarucu, were 

 found throughout the whole extent of the river, although their 

 migrations were evidently limited to movements from shallow to 

 deeper waters, and back again to shoals. 



Even bearing in mind the large number of distinct faunae, we 

 are astounded to hear of the multitude of species inhabiting the 

 river : at the close of his explorations. Professor Agassiz writes to 

 the Emperor of Brazil, " it is very difficult for me to familiarise 

 myself with the idea that the Amazons nourishes nearly twice as 

 many species as the Mediterranean, and a more considerable 

 number than the Atlantic, taken from one pole to the other." 

 And again, " All the rivers of Europe united, from the Tagus to 

 the Volga, do not furnish one hundred and fifty species of fresh- 

 water fishes ; and yet, in a little lake near Manaos, called Lago 

 Hyanuary, the surface of which covers hardly four or five hundred 

 square yards, we have discovered more than two hundred distinct 

 species, the greater part of which have not been observed else- 

 where." He estimates the total number as not less than eighteen 

 hundred or two thousand species. His artist made eight hundred 

 drawings of fish. 



Professor Agassiz' attention was early arrested by a very pecu- 

 liar formation near Rin, whirli he at onrc suspected to be drift ; 



