Greene, H. 1987 10 December (continued) Xenodon rabdocephalus that was very aggressive - striking w/ wide open mouth out of its cage. 11 December La Selva Biological Station, Prov. Heredia, Costa Rica Returned today by O.T.S. vehicle. This morning Orlando Vargas encountered an adult Lachesis muta coiled on the north side of the trail at ~870m on the Sendero Suampo. At ~1400 I walked out to it with Feynner Godinas, Deborah Letourneau, and two friends of theirs, Laura Harriet and Judy Appel. We found the snake in a loose coil at the edge of the trail (not actually on it), with head resting on an outer loop and possibly alert. I estimate its length as 1.7m - adult but not large. Afterwards we returned by way of the Senderos Suampo and Goldridge, in moderate rain all the way. Stopped for a swim at the waterfall, and I started to climb out the first time the rope broke and I fell butt first on Judy's head - a first for us both! As we were clambering about in surprise, Feynner swam up with a large adult ♂ Norops skloopus caught on wet rock face beside the falls, so the five of us had an impromptu lesson on anoles while chatting - teeth and dog paddling. Finally pulled out with some difficulty. 12 December at ~0645 I left with Renaldo Aguilan and Vivien Solis to see the Lachesis muta at S. Suampo 870, but it was gone. I searched surroundings w/out seeing it. Gave an hour lecture in Spanish to the workshop on environmental education.