354 ^ YEAR OF COSTA RICAN NATURAL HISTORY 



feet sinking deeply into the sticky treacherous mud, plunge 

 over fallen logs and scramble up steep slopes. The mud 

 was black above, reddish below, the two quite sharply 

 marked off. I suppose the black layer — which was gritty — 

 was a mixture of vegetable mould and volcanic ash. Over 

 the black and dusting the leaves and horizontal branches 

 was a powdering of the gray ash that fell two days before. 

 Where the trees were thick the undergrowth had received 

 very little, but the exposed surfaces were thickly covered al- 

 though it was not piled up at all. This forest looked very 

 different from that on Irazii. There is none of the weird 

 ghostly grayness of the Irazii forest, and the latter is almost 

 exclusively of oaks. I saw fewer oaks on Poas among the 

 trees whose leaves I could see clearly enough to distinguish 

 at all. Here all trunks and branches, even the stems of small 

 bushes, were thickly covered with soft bright green moss, 

 and the epiphytes were mostly green bromeliads and or- 

 chids. On the lower edge of the woods by the potrero were 

 large quantities of an epiphyte with orange-red flowers, 

 growing high up on big trees, which was very similar to 

 if not identical with, the Loranthus common on Irazu at 

 the level of the Jimenez lecheria. Among the undergrowth 

 there were quantities of Siphocampylus thysanopetalus, in 

 flower. 



From Alajuela to San Pedro de Poas we noticed the ash 

 along the road in about the same quantities. Above San 

 Pedro it was somewhat thicker, and at the lecheria the old 

 man who talked with us said that little stones, from a six- 

 teenth to an eighth of an inch in diameter had fallen with 

 the ash, and that he heard a very loud rushing noise with 

 the beginning of the eruption. When we finally came out 

 of these woods, after two hours of hard climbing, we were 

 on the edge of an irregularly circular "small potrero," with 

 a level, swampy floor, set in a cup-like depression with steep 



