150 A JOURNEY IN BRAZIL. 



rend mon travail doublcment facile en le preparant & 

 1'avance par tous les renseignements possibles. 



Mais je ne veux pas abuser des loisirs de Votre Majest6 

 et je la prie de croire toujours au deVouement le plus complet 

 et a 1'affection la plus respectueuse 



De son tres humble et tres obelssant serviteur, 



L. AGASSIZ.* 



* ON BOARD THE ICAHIABA, OX THE AMAZONS, 



. August 20, 1865. 



SIRE: Allow me to give your Majesty a rapid sketch of the most inter- 

 esting facts observed by me since leaving Rio. The first thing which struck me 

 on arriving at Bahia was the presence of the erratic soil, corresponding to 

 that of Tijuca and the southern part of Minas-Geraes, which I have visited. 

 Here, as there, this soil, identical in its constitution, rests upon rocks in 

 place, of the most diversified character. I have found it also at Maceio, 

 at Pernambuco, at Parahyba do Norte, at Ceara, at Maranham, and at 

 Para. This is a fact, then, established on the largest scale. It shows that 

 the superficial materials which, here as in the North of Europe and America, 

 may be designated as drift, cannot be the result of the decomposition of 

 underlying rocks, since the latter are sometimes granite, sometimes gneiss, 

 sometimes mica or talcose slate, sometimes sandstone, while the drift presents 

 the same composition everywhere. I am as far as ever from being able to 

 point out the origin of these materials and the direction of their transporta- 

 tion. Now that Major Coutinho has learned to distinguish the drift from 

 the decomposed rocks, he assures me that we shall find it throughout the 

 valley of the Amazons. The boldest imagination shrinks from any general- 

 ization on this subject, and yet we must gradually familiarize ourselves with 

 the idea that the cause which has dispersed these materials, whatever it be, 

 has acted on the largest scale, since they are probably to be found all over 

 the continent. Already I learn that my young travelling companions have 

 observed the drift in the environs of Barbacena and Ouro-Preto, and in the 

 valley of the Rio das Velhas. My zoological results are not less satisfactory ; 

 and to speak of the fishes alone, I have found at Para during one week more 

 species than have as yet been described from the whole basin of the Ama- 

 zons, sixty-three in all. This study will be useful, I hope, to ichthyology, 

 for I have already succeeded in distinguishing five new families and eighteen 

 new genera, while the unpublished species do not number less than forty-nine. 

 It is a guaranty of the rich harvest I shall make when I enter upon the 



