Derby.] — M> [May 18, 



which rises in the wooded western portion of the second region, flows for 

 some distance northward, skirting the hase of the Serra de Esperanei, and 

 finally turns westward, entering the third region, and traversing it to the 

 Parana. In the north, forming a part of the northern boundary of the 

 province, is the large river Parana pane ma, which, like the Igaassu, rises 

 in the metamorphic region and traverses the two others, receiving from the 

 province the Itarari, Rio de Cinzas and Tibag} 7 . The latter is, par e.rrel- 

 lencc, the river of the Campos Geraes, in which it rises and flows, to with- 

 in a short distance of its mouth, where it enters the third region. It re- 

 ceives from the north the Pitangui and Yapo, both of which rise in the 

 metamorphic region, about Castro, and enter the sandstone region by deep 

 canons. 



The diamantiferous region is principally in the valley of the Tibagy. 

 Its tributaries, the Yapo and Pitangui, also contain the gems, but are sup- 

 posed to be less rich than the main river, perhaps because of insufficient 

 examination. Fine diamonds are also said to have been found in the Rio 

 de Cinzas. As far as I was able to learn, they have never been found in 

 the Iguassu or Ivahy, although I see no reason why they should not occur, 

 at least in the former river. 



The gems occur in the sands of the river, in the numerous pot-holes, and 

 also in gravel banks, known as dry washings, situated in the campos, at a 

 greater or less elevation above the river. Near the village of Tibagy, are two 

 of these dry washings. One is in a depression of the Devonian shale, in the 

 valley of a small stream, and is only a few metres above the level of the 

 river. It may therefore be supposed to have been deposited by the river, 

 or by the stream that now cuts through the deposit. The section presents 

 below a very irregular deposit of pebbles and sand, a few centimetres in 

 thickness, which is the part washed. Above this are three or four metres 

 of coarse, variegated sand, with pebbles scattered irregularly through the 

 bed, which shows very irregular lines of deposition, as if deposited in an 

 edd} r . Portions of this bed have been cemented by oxide of iron, forming 

 curious, corrugated sheets, globes, and irregular masses, of extravagant form. 

 On top is about a metre and a half of dark-red, structureless clay. The 

 other washing is on a hill side, near the top, at an elevation of about twenty 

 metres above the bed of a small stream, which flows along the hase of the 

 hill, and empties into the river, at an elevation of about 100 metres below 

 the mine. The deposit has evidently been laid down under water, but it 

 can scarcely be attributed to any of the present streams. It also rests on 

 Devonian shale, fragments of which are scattered abundantly through it, and 

 consists of a bed, about three metres thick, of sand and pebbles, in which 

 diamonds are irregularly distributed. Above this are about six metres of 

 structureless, red clay, like that of the first washing. 



The pebbles in both these washings arc well rounded, and consist mainly of 

 quartz and of quartzose rocks, with pebbles of gneiss, and of various other 

 metamorphic and igneous rocks. The red clay continues nearly to the top 

 of the hill, which is a long ridge, with moderate slopes, and extends for a 



