10 



monotonous tract were of great interest. At the Colonia 

 Leopoldina, in southern Bahia, he had the opportunity 

 of observing the customs, etc., of the now nearly extinct 

 Botocudo Indians. 



In the neighborhood of Porto Seguro he explored the 

 coral and sandstone reefs, which latter are such a prom- 

 inent feature on the Brazilian coast. He was the first to 

 carefully work out the structure and mode of formation 

 of these sandstone reefs, although Darwin's short descrip- 

 tion of them is not far from correct. 



After Hartt had returned to the United States from 

 the Tha)'er Expedition, he felt that he had left unfinished 

 some of the more important of the investigations he had 

 made in Brazil. He was unable to report as fully as he 

 wished on many subjects of interest which he had in part 

 studied. So in 1867 he returned to Bahia, to better perfect 

 his old work and continue his observations. He worked 

 out the geology on the line of the Bahia railroad in detail, 

 and collected some fossils from the Cretaceous formations 

 which compose much of that region. He also studied 

 the structure of the Abrolhos Islands and Reefs, which 

 lie off the coast of Bahia, to the southeast of the town of 

 Caravellas. The islands are of stratified deposits, cap- 

 ped with trap, while the reefs, which had never before 

 been to any extent examined by a naturalist, are ol coral 

 generally assuming curious tower-like forms, and often 

 growing together to form a large connected expanse. 



In addition to throwing new light on the formation of 

 certain kinds of coral reefs, he also discovered a large 

 number of species of corals, of which the majority were 

 new, but belonged to West Indian types. The entire 

 absence from the Brazilian coast of many prominent 

 West Indian genera, such as Madrcpora, Mcandrina, Diplo- 

 ria, etc., was noted by him. The Cretaceous region of 

 Sergipe was visited, and yielded many fossils, which have 

 been in part described by Prof. A. Hyatt. 



In the short interval which elapsed between his first 

 and second trips, he was engaged in scientific teaching 

 and lecturing in, and near, New York city, at the Cooper 



