RESIDENCE AT TARAPOTO 99 
The ridges and peaks are of white sandstone, as 
are those of the Andarra farther up the river. 
Both are very bare of vegetation, being burnt 
almost every year and overrun with the common 
fern Pteris caudata. The ascent to Potrela up the 
rocky valley of the Cuchi-yacu is, however, through 
luxuriant forest especially rich in ferns and mosses. 
To conclude this sketch of the Tarapoto district 
investigated by Spruce, I will give a few passages 
translated from his "Precis d'un Voyage" pub- 
lished in the Revtte Bryologique for 1886 : — 
" The first thing that strikes the eye of the 
botanist at Tarapoto is the abundance of ferns. 
These plants are by preference, as we know, either 
maritime or subalpine. On the hills of Brazil a 
tolerably large number of species are found, but in 
the interior of the continent and in the great plain 
of the Amazon valley, although ferns are not 
wanting, yet the species are never numerous and 
several of them repeat themselves at every step 
even up to the roots of the Andes. One may 
therefore judge of the riches of the Eastern 
Cordillera of Peru in ferns by the fact that there, 
within a circle less than fifty miles in diameter, 
the author found 250 species of ferns and their 
allies, of which many were new, especially among 
the tree-ferns." 
Among the most interesting plants in this 
region, next to the ferns, may be named the 
Rubiaceae, of which Spruce collected 98 species. A 
small number of these were already known through 
the researches of Ruiz and Pavon, Poeppig and 
Matthews, but the majority were new. The 
" Precis " then continues : — 
