Lisboa — Permian Geology of Northern Brazil. 425 



Art. XXXVI. — The Permian Geology of Northern Brazil ; 

 by Miguel Arkojado R. Lisboa. 



Introductory. — In 1909, when employed by the Servico 

 Geologico do Brazil to make a geological reconnaissance in the 

 northern and northeastern states of that country, I was espe- 

 cially requested to investigate the supposed occurrence of 

 Psaronius in the state of Piauhy. 



The city of Para was selected as a convenient starting point 

 for the expedition, and in the natural history museum at that 

 place I found a characteristic specimen of Psaronius not more 

 than a decimeter in diameter. It was not labeled, but was 

 reported to have come from the state of Maranhao, and to have 

 been received as a gift. 



Afterwards I made inquiries in the city of Maranhao among 

 the collectors of mineral specimens, and among the many exam- 

 ples of fossil plants examined, almost all of them angiosperms, 

 I had the good fortune to find a trunk of a typical and beauti- 

 fully preserved Psaronius^ about 40 centimeters in diameter. 

 This specimen was in the corner of a hall in the Episcopal 

 Seminary and had long been used as a seat in the chapel or 

 cathedral by the Rev. Alvarenga, late bishop of the diocese. 

 Through the courtesy of the Rev. Galvao, governor of the 

 bishopric, this fine trunk has been sent, at my request, to the 

 collections of the Servico Geologico do Brazil at Rio de Janeiro. 



The locality from which it came was known only very 

 vaguely. The Bishop had received it as a gift from the Rev. 

 Manoel Goncalves Ribeiro in the year 1889 or thereabouts, 

 while making a pastoral visit through the province. The Rev. 

 Ribeiro had died while vicar in S. Francisco, but I learned 5 

 definitely that the trunk had originally been found in the 

 region of the Parnahyba river above the city of Floriano. 



With this and many other indications of geological occur- 

 rences of various natures, I was enabled to outline a trip, having 

 in view a general geological reconnaissance of the state of 

 Maranhao and of the north of Goyaz. This plan was success- 

 fully carried out. With the help of an assistant, the topogra- 

 pher Hans Baumann, I resolved to visit convenient points in 

 the interior of the state, meandering it in directions approxi- 

 mately east-west and north-south, and having our traverses 

 frequently tied up. Thus we would have an opportunity to 

 observe the various beds of the Pindare, Grajahu, Mearim, 

 Corda, Alpercatas, Itapicuru, Balsas, and Parnahyba rivers in 

 different places, and at the same time to examine, in the stream 

 channels, the underlying sediments which are elsewhere cov- 

 ered with sand. 



