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60 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. : 
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which are not it is desirable to know the probabilities of their success 
and whence they may be most conveniently obtained. | 
REFERENCES TO BOTANICAL LITERATURE. 
There is as yet nothing like a complete list of the plants of Porto 
Rico, and most of the literature is not even indexed. It has there- 
fore seemed desirable, as a matter of convenience for those who may 
wish to become more familiar with the flora of the island, to add 
references to descriptions of many of the species enumerated below, 
although in the present paper no attempt has been made to follow the 
method or arrangement of formal botanical literature. Nor should it 
be inferred that the author cited is in all cases responsible for the 
statements accompanying a specific reference, although this is gen- 
erally true where very short notes are given. The more recent liter- 
ature of Urban has been cited in preference to the older writings in 
order to avoid multipleation of references, and because Urban gen- 
erally gives complete synonymy from which the opinions of other 
writers ean be traced. 
BOOKS ON PORTO RICAN PLANTS. 
The botany of Porto Rico is far from complete, and very little of it has 
been written in the English language. Descriptions of plants found in 
Porto Rico are scattered through a vast number of publications which 
can not be enumerated here, but brief notices of the more important 
papers may not be out of place. But two authors have attempted a 
connected sketch of the Porto Rican flora, and the efforts of these not 
only remain incomplete in that they do not cover the entire series of 
families of flowering plants, but the lists are also pa:tial and loeal, as 
the writers themselves realized. 
The first of these sketches was that of Don Domingo Bello y Espi- 
nosa.“ This consists almost entirely of a list of plants occurring, as 
explained by the author, in the triangular area included - between 
Aquadilla, Lares, and Guanica. The prefatory note states that the 
writer resided in Porto Rico for thirty years, presumably at Maya- 
guez, and that his botanical studies were carried on in the intervals 
of a busy professional life. Considering this fact and the other diffi- 
culties under which he must have labored, the result is certainly 
most creditable, and the field observations and notes represent a 
distinct contribution to our knowledge cf the flora of the area coy-— 
ered, although the adjustment of Bello’s systematic treatment has 
given his successors considerable trouble. Many popular names are 
given, but no economic notes are included, although the useful species 
«Domingo Bello y Espinosa. Apuntes para la flora de Puerto-Rico. Anales de 
la Sociedad espanola de historia natural, tomo X, pp. 250-304, 1881; tomo XII, pp. 
103-130, 1883. 

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