1879.] -'■'" [Derby. 



On the Curua, Mr. Smith found, above the beds of undoubted Devonian 

 age, a small series of unfossiliferous sandstones, and then at Praia Grande, 

 loose silieified fossils, identical with those of Itaituba, which indicate the 

 presence of a bed of limestone. Above this there is a series, the estimated 

 thickness of which is 600 feet, composed of alternations of soft sandstones 

 and sandy shales, of which certain layers near the upper part, exposed at 

 a place called Pacoval, are highly fossiliferous. At lake Cujubim, near the 

 river Maecuru, the section begins below with massive beds of yellow sand- 

 stone of undetermined thickness ; then comes two feet of hard sandstone, 

 followed by a bed five feet thick, of impure, silicious, fossiliferous lime- 

 stone, which is separated by ten feet of sandstone and shale from a bed of 

 equal thickness of pure limestone, containing fossils identical with those of 

 Itaituba ; above this are soft beds of sandstone and shale, with fossils identi- 

 cal with those of Pacoval on the Curua. In various other localities in the 

 vicinity of Alenguer, Mr. Smith found exposures of sandstone and shale 

 of very varied characters, which appear to belong above the series at 

 Cujubim, and to represent, in part at least, the upper portion of the Curua, 

 section. Mr. Smith well observes that the variation in the character of 

 these Carboniferous beds, in both their horizontal and vertical extension, 

 indicates deposition in shallow water, during subsidence. The limestone 

 appears to be always near the base of the series. 



The exposures of Carboniferous rocks on the Trombetas are so unsatis- 

 factory, that they scarcely do more than prove the existence there of sand- 

 stones, shales and limestones, with fossils identical with those of the other 

 localities. 



The Carboniferous fauna of the Amazonas is very rich, containing more 

 than a hundred species of Brachiopods, Lamellibranchs, Gasteropods, Corals, 

 Bryozoans, Echinoderms, Fishes and Trilobites. Of these, I have already 

 published descriptions of the Brachiopods of the Tapajos,* and hope soon 

 to give descriptions of the remainder. The fauna shows the closest relation- 

 ship to that of the Coal Measures of the Western States, more than half 

 of the species being identical. I have already shown that the Bolivian and 

 Peruvian Carboniferous faunas, as far as they are known, are equivalent 

 to the Brazilian, and to that of the North American Coal Measures. 



The following are some of the most important species common to the three 

 regions : Spirifera camerata Morton (8. Condor D'Orb), Athyris subtilita 

 Hall, Retzia Mormonii Marcou (R. punetulifera Shumard), Productus Cora 

 D'Orb., Productus semirelicuhtttis Martin, and Chouetes glabra Geinitz. 

 The following are, among others, in addition to the above, common to 

 Brazil and the United States : Spirifera roekymontana Marcou, Spirifera 

 planoconvexa Shumard, Spirifera perplexa McChesney, Myalina kansas- 

 ensis Shumard, Allorisma subcuneaia Meek and Hayden, Amculopecten 

 oecidentalis Shumard, Aviculopeclen carbonaria Stevens, Schizodus Wheeleri 

 Swallow, Lima retifera Shumard, EntoUam aviculatum Swallow, Bellero- 

 phon carbonarius Cox, Rhombipora lepidodendroides Meek, and Synocladia 

 biserialis Swallow. 



* Bulletin of the Cornell University (Science^ Vol. I, No. 2, 1874. 



