MANAOS AND ITS NEIGHBORHOOD. 299 



the dog of pure type the favorite companion of civilized 

 man. The question respecting the relation of the human 

 races to each other is complicated by the want of precision 

 in the definition of species. Naturalists differ greatly in 

 their estimation of the characters by which species are to 

 be distinguished, and of their natural limitations. I have 

 published elsewhere my own views on this subject. I 

 believe the boundaries of species to be precise and un- 

 varying, based upon a category of characters quite distinct 

 from those on which the other groups of the animal king- 

 dom, as genera, families, orders, and classes, are founded. 

 This category of characters consists chiefly in the relation 

 of individuals to one another and to their surroundings, 

 and in the relative dimensions and proportions of parts. 

 These characters are no less permanent and constant in 

 the different species of the human family than in those 

 of any other family in the animal kingdom, and my ob- 

 servations upon the cross-breeds in South America have 

 convinced me that the varieties arising from contact be- 

 tween these human species, or so-called races, differ from 

 true species just as cross-breeds among animals differ from 

 true species, and that they retain the same liability to 

 revert to the original stock as is observed among all so- 

 called varieties or breeds." 



Our visit to Mauhes will be the pleasanter and doubtless 

 the more successful, because Dr. Epaniinondas, who has 

 already done so much to facilitate the objects of the ex- 

 pedition, takes this opportunity of visiting a region with 

 which, as President of the province, he is desirous of be- 

 coming acquainted. He is accompanied by our host, Mr. 

 Honorio, whose house has been such a pleasant home for 

 us during our stay in Manaos, and also by Mr. Michelis, 



