376 A YEAR OF COSTA RICAN NATURAL HISTORY 



each other, in others scattered but at intervals less than their 

 own dimensions; in still other places they were yet farther 

 apart. Owing to their dark color, in contrast to the gray 

 boulders on Irazu and near Cartago, they gave a somber ap- 

 pearance to the ground which they cover. Where they came 

 from I do not know, as there is now no peak or cone near. 

 Specimens brought from here have been identified as porphy- 

 ritic scoriaceous basalt with large plagioclase phenocrysts. 



On December 21, Professor Tristan and P. walked along 

 the railroad track westward to Atenas station, about seven 

 kilometers distant, collecting some insects on the way. We 

 passed some "poro-poro" trees {Cochlospermum hibiscoides), 

 conspicuous objects wherever they grow because they blos- 

 som when entirely leafless. The flowers, bright yellow in 

 color and two to four inches across, are borne over the 

 rather flattened crown of the tree. The "poro-poro" is 

 entirely different from the "poro" (Erythrina sp.) in spite 

 of the similarity of the vernacular names. Nor must it be 

 confounded with the "corteza" described below, a larger 

 tree which also covers itself with brilliant yellow flowers in 

 its leafless condition and is equally conspicuous. Coch- 

 lospermum hibiscoides belongs to the Bixaceae; its leaves are 

 palmate. The flowers have five sepals (two green, three 

 pale yellow) five bright yellow petals, numerous greenish- 

 orange stamens which are chiefly grouped in five masses 

 opposite the petals. Sepals, petals and stamens persist as 

 shrivelled remains at the base of the fruit. This is a five- 

 valved ellipsoidal capsule, opening on the tree so as to show 

 the papery ridges inside the valves, bearing the dark brown 

 kidney-shaped seeds to which are attached masses of white 

 cottony fibers. The mature seeds appear to be but a small 

 proportion of the ovules as many more undeveloped seeds 

 were usually found in the fruits. The poro-poro belongs 

 to the lower Pacific slope; the highest point at which we saw 



