492 BOTANICAL INFORMATION. 



The first night was passed at only a league's distance from 

 the city, at a place on the hill called Olho d'Agoa. This hill, 

 traversed by a steep, ill-made road, is said to contain much 

 gold in its sifted sandstone courses of quartz ; the inhabitants, 

 however, have for many years ceased to make any search for 

 it, nor are the numerous gold mines, originally discovered by 

 the first conquerors of this country, any longer wrought. 

 The similarity between the vegetable productions of this dis- 

 trict and those of Minas Geraes, certainly favours the idea 

 that this valuable metal does exist here, though perhaps in 

 very small quantities. 



On the 12th of May, at Inhuma, seven leagues distant 

 from Oeiras, we crossed the Rio Caninde, here an insignifi- 

 cant stream. In general features, the country much resem- 

 bles what we had seen before reaching Oeiras ; ponds, however, 

 are more frequent in the vallies and together with the Carnaiiva 

 Palm, the Buriti and Uricuri (Mauritea fleanwsa, L. and 

 Attalea compta, M.) unite to form extensive forests, which 

 give both a peculiar and majestic character to the landscape. 

 Here, too, were sandstone hills, rising in successive terraces, 

 their lofty tops flattened into extensive plains, while between 

 these elevations lay wide valleys, whose grey-green vegeta- 

 tion strikingly contrasted with the red colour of the stone. 

 It was more and more visible on this track how the elevated 

 part of Piauhy differs in its Mimosa vegetation from the 

 lower Piauhy, where the Agreste every where prevails. 



To the left lay the isolated Serra de Mocambao, of which 

 we made the circuit, passing through many of the declivities 

 and lower parts of the mountain, where we had to wade 

 through crystal brooks, and were frequently obliged to make 

 our way with difficulty on the swampy paths, through unex- 

 plored and untracked woods. We often saw on the sand- 

 stone many large pieces of very beautiful Fortification Agate. 

 Not being always able to reach a farm at night, we were 

 obliged to pass the hours of darkness in the open air, and the 

 rain which regularly fell between sunset and midnight, was 

 by no means favourable to the removal of our feverish symp- 



