540 APPENDIX. 



Geraes, collecting on the way at the Rio Urucu, and afterwards at 

 Philadelphia. Along the coast, and indeed throughout his whole 

 journey, Mr. Hartt continued his geological observations, which 

 he carefully recorded. From Philadelphia he and his companion 

 proceeded by land to Calhao, on the Rio Arassuahy ; making a 

 detour from Alahii to Alto dos Bois, in order to study the drift and 

 the geological structure of the elevated Chapadas. At Calhao they 

 also made good collections of fishes. Returning to Calhao from a 

 visit to Minas Novas and a study of its gold-mines, Mr. Hartt de- 

 scended the Rio Jequitinhonha three hundred and sixty miles to 

 the sea. Mr. Copeland had preceded him in order to make an 

 excursion to Caravellas ; and they met again at Cannavieiras. 



At Cannavieiras they made good collections, and then ascended 

 the Rio Pardo to its first fall, fishing and geologizing along their 

 route. They visited also Belmonte, and then went southward to 

 Porto Seguro, where they stayed for several days, collecting corals 

 and marine invertebrates. Here, as at several other points along 

 the coast, Mr. Hartt made a careful examination of the stone-reefs. 

 His researches on these " recifes," which constitute so remarkable 

 a feature along the Atlantic coast of Brazil, are exceedingly inter- 

 esting ; and I do not know that any geologist has made a more 

 careful and connected examination of them. He believes them to 

 be formed by the solidification of beach ridges ; the lower part of 

 which being cemented by the lime dissolved from the shells con- 

 tained in them remains intact, while the upper portion was carried 

 off by storms ; thus leaving a solid wall running along the coast, 

 broken through here and there, and divided from the land by a 

 narrow channel. He studied the coast reefs both at Santa Cruz 

 and at Porto Seguro, and ascertained their southward extension to 

 the Abrolhos. From Porto Seguro Messrs. Hartt and Copeland 

 went northward to Bahia, touching at several points along the coast, 

 and thence returned to Rio de Janeiro, whence we sailed together 

 for the United States in the month of July, 1866. 



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