1865-67.] LECTURE AT PARA. 151 



was not only never finished, but was hardly begun, 

 except some years later in the case of the fishes only, 

 by his assistant, Dr. Steindachner. This is much to be 

 regretted ; for if he had accomplished what he planned 

 before he started on that expedition, it would have 

 resulted in a great advance in our knowledge of the 

 geographical distribution of aquatic animals. In his 

 own words, " One of my principal objects during the 

 whole journey was to secure accurate information con- 

 cerning the geographical distribution of the aquatic 

 animals throughout the regions we visited. Upon this 

 subject we had little precise knowledge, - - even the 

 best known among the fishes, reptiles, etc., of the 

 Brazilian waters being entered in our zoological records 

 simply as living in Brazil, or more generally still, as 

 found in South America. As the distribution of species 

 lies at the very foundation of the question of their 

 origin, I have aimed at ascertaining as far as possible 

 what are the areas and limits of their localization." It 

 is a pity that he did not accomplish this localization ! 



Before leaving Para, Agassiz delivered a lecture on 

 the physical history of the valley of the Amazons, which 

 was afterwards published in " The Atlantic Monthly," 

 Vol. XVIII., July, August, 1866, pp. 49-60, 159- 

 169, and reprinted in "A Journey in Brazil," Boston, 

 1868. The month of April, 1866, was devoted to an 

 exploration of the province of Ceara, with the special 

 purpose of looking for traces of ancient glaciers. The 

 time was not propitious ; it was the rainy season, and it 

 was not easy to reach the Sierra of Aratanha in the 

 interior of the province. However, Agassis succeeded 



