A MA ZONIA N UPPER CA RB ONIFER O US FA UNA . 485 



(occurring also at Pedra do Barco) are the only distinct forms 

 among the 10 in the limestone at the Serra de Tajauri. The 

 beach specimens from Praia Grande on the Curua are exactly 

 similar to those from Itaituba, and of the 12 species known from 

 that place only an undetermined Atliyris has not appeared at 

 Itaituba. The yellow shale, probably a decomposed limestone 

 from Lake Arapicu with 1 1 species and the limestone and shale 

 of Lake Abui with five, show the same close relationship and 

 indicate that the limestone extends westward to the Trombetas. 

 None of the fossils from the Rio Uatuma, still farther to the 

 westward, have been seen by me, but according to the note of 

 Sr. Barbosa Rodregues they agree in character and mode of 

 occurrence with those of Itaituba. 



The fauna from the shale at Pacoval on the Curua is thought 

 by Mr. Smith to come near the top of about 600 feet of shale 

 above the limestone furnishing the beach specimens of Praia 

 Grande. The rock is decomposed and of a marly aspect, indi- 

 cating a high original proportion of calcareous matter. Of its 37 

 species, 10, all lamellibranchs, have not been found at Itaituba, 

 the others occurring at that place mainly in the cherts and boulders 

 in which also occur the three {Productus corn, P. nebrascensis and 

 Streptorhynchus correianus) out of its 13 brachiopod species 

 that have not been found in the Bom Jardim limestone. The 

 shaly beds at Lake Cujubim and Lake Curucaca in the Alemquer 

 district, also placed above the limestone by Mr. Smith, agree, so 

 far as their fossils can be made out, with the Pacoval fauna. 



Thus, although there is on the Lower Amazonas a consider- 

 able thickness, probably from 1,000 to 2,000 feet, of supposed 

 Upper Carboniferous rocks, all the known fossils are marine and 

 from a single, or two closely related horizons. As stated in my 

 paper on the brachiopods and afterwards confirmed by an exami- 

 nation of a collection brought from Lake Titicaca by Prof. 

 Alex. Agassiz (Bull. Mus. Comp. Zool., No. 12) the Andean 

 Carboniferous fauna is of about the same horizon. In southern 

 Brazil, where there is an extensive Carboniferous area, fresh- 

 water conditions seem to have prevailed and marine fossils have 



