LONDON, AND VOYAGE TO SINGAPORE 325 



Amazon, either wild or in a state of captivity, with the par- 

 ticular object of pointing out their peculiarities of distribu- 

 tion. As with butterflies and many birds, I found that both 

 the Amazon and the Rio Negro formed the limit to the range 

 of several species. The rare monkey, Lagothrix Humboldti, 

 inhabits the district between the Rio Negro and the Andes, 

 but is quite unknown to the east of that river. A spider- 

 monkey (Ateles paniscus) is found in the Guiana district 

 up to the Rio Negro, but not beyond it. The short-tailed 

 Brachiurus Couxiu has the same range, while distinct species 

 are found in the Upper Amazon and the Upper Rio Negro. 

 The two species of sloth-monkeys (Pithecia) are found one 

 to the north the other to the south of the Upper Amazon. 

 In several other cases also, as well as with the beautiful 

 trumpeters among birds, the great rivers are found to form 

 the dividing lines between quite distinct species. Four great 

 divisions of eastern equatorial America, which may be termed 

 those of Guiana, Ecuador, Peru, and Brazil, are thus distinctly 

 marked out by the Amazon and its great northern and south- 

 ern tributaries — the Rio Negro and the Madeira river ; and it 

 seems easy to account for this if we look upon the vast central 

 plains of South America, so little elevated above the sea-level, 

 as having been formerly a gulf or great inland sea which has 

 been gradually filled up by alluvial deposits from the sur- 

 rounding highlands, and to have been all stocked with forms 

 of life from the three great land-masses of the continent. 

 These would be diversely modified by the different conditions 

 of each of these areas, and as the intervening seas became 

 formed into alluvial plains drained by a great river, that river 

 would naturally form the dividing line between distinct but 

 closely allied species. 



It was in the autumn of 1853 that I made my first visit 

 to Switzerland with my friend Mr. George Silk. On our way 

 from London to Dover we had for companion in our com- 

 partment a stout, good-humoured American, a New England 

 manufacturer, going to Paris on business for the first time. 

 He asked us if we could recommend him a good kafe. On 



