Heere, H. 1983 24 June (continued) for 23 June - checked lachesis periodically throughout day and evening. Caught an adult Sibon nubilata on steps below the station after dark. It expelled foul stuff from cloaca and thrashed late this afternoon Manuel Santana brought in the 3m Boa constrictor he's been tracking in forest near Edwin Paniagua's finca. She was in a huge tree root, and is opaque. 25 June Checked little jelenetared lachesis at 0540h. At 0632 h Edwin Paniagua led us to a 2m+ Lachesis muta ~50m from the Bath House, in the Ecological Reserve. It was coming on to the shortcut trail and bumped his foot (not stuck), then turned SE and crawled slowly back into the forest. When we approached it was stretched out immobile, and while ~10 people stood around and took photos, the only movements were a flinch or two in the neck region when a flash went off. Returned ~0715 and it was ~20m SW of that place, crawling slowly. Stopped when we approached. Then Pat Fogden and I watched it stretched behind a tree from ~30m away while Michael went for his camera. Suddenly it had disappeared, so we circled to the tree and past it, then each searched around nearby large buttressed trees. We were amazed it had moved off