540 APPENDIX. 

Gerae?, 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 Calhdo, on the Rio Arassuahy ; making a 
detour from Alahii to Alto dos Biois, 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. 
Cambridge : Stereotyped and Printed by Welch, Bigelow, & Co. 
