Reviews — Agassiz's Journey in Brazil. 457 



present volume is gratefully inscribed." Thus reads the dedication, 

 and we present!}^ learn that when, in the winter of 1865, it became 

 necessary for Professor Agassiz to seek a change of climate, he began 

 to brood over his long-cherished wish to visit Brazil. Single- 

 handed, this journey, however pleasant as a vacation, would produce 

 very little result, and would thus possess no charm for him. Under 

 these circumstances, and while the Professor was still in a state of 

 perplexity, he met Mr. Nathaniel Thayer, who said in reference to 

 the proposed journey : — " You wish, of course, to give it a scientific 

 character ; take six assistants with you, and I will be responsible for 

 all their expenses, personal and scientific." We can well believe 

 that the Professor doubted at first whether he had heard rightly. 

 Such generosity is not of every-day occurrence, and is the more un- 

 usual, from the simple, unostentatious manner in which it was offered, 

 and the large and liberal manner in which it was carried out. 



This volume does not profess to contain the results of the expedi- 

 tion ; many of them have to be worked out, and may require years 

 of labour to evolve. What it professes to be, and what it really 

 consists of, is a journal or diary written by Mrs. Agassiz, with inter- 

 spersed remarks by the Professor ; he was in the habit of giving 

 her daily the more general results of his scientific observations ; 

 and, in a few places, we find a scientific essay, which has evidently 

 been written by him. 



The journey was from Kio de Janeiro, up the Amazon to Taba- 

 tinga, and back to Manaos. From this place excursions were made 

 up the tributaries of the Amazon, and finally the party returned 

 to Eio, after the lapse of more than a twelvemonth. 



It would be next to impossible for any observing naturalist to 

 spend a whole year on the Amazon without finding something 

 astonishing ; but we question whether many men would have found 

 the marvels there which Professor Agassiz seems to have done. We 

 have nothing to do with the 2000 species of fishes which he states 

 that he has collected, nor with the 200" species which inhabit, and 

 are nearly confined to, a small pond covering a space of not more 

 than four or five hundred square yards. All this sort of thing must 

 be provisionally accepted until the figures and descriptions are pub- 

 lished, and then we shall expect the Zoologists to say something about 

 them. What we, as Geologists, have to do with, is Prof. Agassiz's 

 assertion that, during the Glacial periods, the whole valley of the 

 Amazon and its tributaries was occupied by an enormous glacier. 



Let us now endeavour to follow Professor Agassiz in his wonder- 

 ful interpretation of the geological history of the valley of the 

 Amazon. 



This valley was first sketched out by the elevation of two tracts 

 of land ; namely, the plateau of Guiana on the north, and the central 

 plateau of Brazil on the south. At a later period the upheaval of the 

 Andes took place, closing the western side of this strait, and thus 

 transforming it into a gulf open only towards the east. At the close 

 of the Secondary period, the whole Amazonian basin (including in 

 this term the provinces of Ceara, Pianhy, and Maranham) became 



VOL. V. — NO. LII. 30 



