PENDULOUS NESTS 263 



fact, Dr Goeldi has made the following observations, 

 which I herewith quote from the Ibis (1897, pp. 364, 

 365): — "Just as the material used by Cassicus 

 persicus for its nest in Bahia (and southwards) is 

 different from that used by the same bird in Para, 

 the material employed by Ostinops decumanus in 

 these two countries respectively is also different. I 

 have stated that in Southern Brazil Ostinops uses 

 exclusively the Barba da velho {Tillandsia usneoides), 

 and that these southern nests are of a greyish colour. 

 On the Amazon the material employed by this bird 

 is composed of — (1) a black hairy substance, very 

 like horsehair or delicate and elongated roots [which 

 botanical researches in the Para Museum prove to 

 be a most interesting lichen, but of which it is not 

 yet possible to ascertain the exact systematic name] ; 

 (2) of the dry and tender roots of certain orchids of 

 a yellowish colour. As the proportions of both sub- 

 stances is almost as two to one, and the black root- 

 like lichen is largely predominant, the general aspect 

 of these northern nest-bags is of a blackish colour, 

 contrasting in a striking manner with the greyish 

 Tillandsia-structures of Southern Brazil." We thus 

 see how a species may change its nest material with 

 the change of vegetation in different latitudes — a 

 phenomenon of which vast numbers of other in- 

 stances might have been given, and of which not a 

 few have already been indicated in the present 

 volume. But to return to the nests of these Icterine 



