Rathbua.] 352 [April 17, 



discovered Palaeozoic rocks with many fossils whose exact age -has not 

 yet been determined. The genera of Brachiopods represented are Dis- 

 cina, Spirifera, Strophodonta, Streptorhynchus, Leptocoelia (?), etc.; 

 a small Ophiuran was very abundant. To complete the scientific work 

 done to the south of Rio de Janeiro in connection with the Geologi- 

 cal Commission, we must add the scientific results of a trip made by 

 Mr. J. E. Mills to the gold regions of Rio Grande do -Sul, of which a 

 report was kindly furnished Prof. Hartt. Mr. Mills also contributed 

 a very valuable report on the gold regions of Minas Gerses. 



From July 1876 to February 1877, while the above described ex- 

 plorations were in progress to the south of Bahia, Mr. Derby was 

 arriving at most important results in the valley of the Ainazonas, 

 which region he was well fitted to investigate, by reason of his for- 

 mer experiences there. He was accompanied by Sfir. Freitas and 

 Mr. H. H. Smith, the latter of whom had already spent two years on 

 the Amazonas in studying its entomology and the geology of several 

 sections. The most valuable, connected series of .explorations by 

 the Commission were those executed by this small party. They ex- 

 amined the Erere-Monte-Alegre distinct, the Rio Maecurii, wholly 

 unknown to science, and the Rios Curua and Trombetas, making 

 maps of the entire region. Mr. Smith alone worked up minutely 

 the district lying between Alenquer and the Msecuri-i, and reexam- 

 ined the Carboniferous of the lower Tapajos. There was demon- 

 strated 'to -exist to the north of the Amazonas a large series of 

 Palaeozoic fossiliferous rocks, including the Upper Silurian, Devonian 

 ■and Carboniferous. The most important discovery was, that the 

 ■Carboniferous of the lower Tapajos, and that of Maue-assii, extend to 

 the north of the Amazonas, from the Trombetas far to the east of 

 Monte Alegre. This fact is proved to a certainty by the stratigraphy 

 of the beds and by their fossils. The same species of fossils that 

 occur at Itaituba were found on the Trombetas and Curua, in the 

 district of Cujubim, and in Tajury. The existence of a Carbon- 

 iferous basin on the Amazonas, occupying an immense area, is thus 

 settled beyond doubt; but the important question, " does it contain 

 eoal ?" has not yet been answered. The region is generally so cov- 

 ered with a dense vegetation, and so level, that it is next to impossi- 

 ble to find any exposures of rock, except about the falls of the prin- 

 cipal tributaries. On the Msecuru and Curua, to the north of Erere, 

 was found a rich Devonian fauna, differing only slightly from that 

 already known from the latter locality. The Upper Silurian fossil- 



