330 ZOOLOGY OF THE AMAZON DISTRICT.
of the north-western tributaries of the Rio Negro, so that it seems probable that distinct species of this genus inhabit the opposite shores of the Amazon.
The cock of the rock, Rupicola crocea, is, on the other hand, an example of a bird having its range defined by a geological formation, and by the physical character of the country. Its range extends in a curving line along the centre of the moun- tainous district of Guiana, across the sources of the Rio Negro and Orinooko, towards the Andes; it is thus entirely com- prised in the granite formation, and in that part of it where there are numerous peaks and rocks, in which the birds make their nests.
Whether it actually reaches the Andes, or occurs in the same district with the allied R. Peruviana, is not known, but personal information obtained in the districts it inhabits, shows that it is confined to the narrow tract I have mentioned, between i° south and 6° north latitude, and from the mountains of Cayenne to the Andes, south of Bogota
Another bird appears bounded by a geological formation. The common red-backed parrot, Psittacus festivus, is found all over the Lower Amazon, but, on ascending the Rio Negro, has its northern limit about St. Isabel, or just where the alluvial country ends and the granite commences; it also extends up the Japura, but does not pass over to the Uaup£s, which is all in the granite district.
The fine blue macaw (Ara hyacinthina) inhabits the borders of the hilly country south of the Amazon, from the sea-coast probably up to the Madeira. Below Santarem, it is sometimes found close up to the banks of the Amazon, but is said never to cross that river. Its head-quarters are the upper waters of the Tocanti'ns, Xingii, and Tapajoz rivers.
As another instance of a bird not crossing the Amazon, I may mention the beautiful curl-crested Aracari (Pteroglossns Beauharnaisii), which is found on the south side of the Upper Amazon, opposite the Rio Negro, and at Coari and Ega, but has never been seen on the north side. The green Jacamar of Guiana also {Galbula viridis) occurs all along the north bank of the Amazon, but is not found on the south, where it is replaced by the G. cyanocollis and G. maadicauda^ both of which' occur in the neighbourhood of Para.
