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Alegre, Ji sulphur-spring bubbles up through the Devonian shales. 

 The water is limpid, of a greenish tinge, and with a strong sulphu- 

 reous odor and taste ; notwithstanding which, the basin in which the 

 water collects is inhabited by little fishes and a species of Ampulla- 

 ria. I regret that I failed in an attempt to bring away some of the 

 water for analysis, especially since at Monte-Alegre it has consider- 

 able repute for its medicinal qualities. 



Going eastward from the igarape along the Monte-Alegre trail, 

 one rises by an ascent of a few feet from the alluvial flat to the De- 

 vonian plain, that, almost as level as a floor, stretches to the foot of 

 the Monte-Alegre highlands, beneath which the Palaeozoic beds dis- 

 appear. The surface is quite destitute of soil and is strewn with 

 little nodules of iron-stone, so that large areas are quite barren both 

 of wood and herbage. 



Just before reaching the Monte-Alegre highlands, several slight 

 elevations, only a few feet high, are met with, that show, in place, 

 light-colored shales, with thin bands of a reddish sandstone, some 

 of which are full of fossils, StrcjJtoj'liynchus Agassizii, nob., being 

 especially abundant. At this locality I obtained a single glabella 

 of what appears to be a new species of Homalonottis. 



If we now retrace our steps to the igarape, and follow the path to 

 the village of Erere, we shall find the Devonian beds forming a 

 flat or rolling, open campo, with long, gentle ascents and descents, 

 in the rain-courses of which are indifferent exposures of whitish 

 shales, apparently nonfossiliferous. On this campos-land there is 

 very little soil, what there is being baked hard and strewn with 

 small, angular fragments of red sandstone, that occasionally fur- 

 nish fossils. The surface is often covered with little, rounded iron- 

 stone nodules, scarcely larger than beans, sometimes forming a 

 continuous layer. The q^mpo is sparingly clothed with coarse 

 grass, trees being few, scattered, stunted and disfigured by campos 

 fires. Occasional large, arborescent cactuses heighten the dry, bar- 

 ren appearance of the landscape. The low places are covered Avith 

 Avoods densely filled in, on the drier grounds, with Curud palms. 



Between the igarape and the village of Erere are several large 

 dykes that project above the surface like ruined walls, but the vein- 

 rock is always badly decomposed, so that it is difficult to say what 

 it originally was. Similar dykes occur in all parts of the plain. 



