Greene, H. 1987 21 July (continued) Bothrops asper crawling rapidly off the trail. Turned sideways and bit when pinned w/ my boot. Next we turned south on the LOC and checked the Lachesis muta first spotted by Rocio Lopez on the 17th. Found it coiled and "asleep" at the same site, fully exposed but difficult to see on leaf litter. The snake is <1m W of a large (.5-1m Ø) old fallen log. Once when I was leaning over the log it flinched once, but otherwise we didn't disturb the snake. Walked in on the LOC and CES, and ≈1015hr found the L. muta missing at CES S30. Bruce, Dave and I picked up a receiver and went right out and soon picked up a weak signal, but couldn't get it focused into a sharp beep at first because of interference. As I was slowly walking and searching I stepped inadvertently on a <1m "Philodendron" and as the plant bent over saw a "large yellow snake" - adult Lachesis muta ! - drawing back from my right heel. This new snake is ≥2m ad very fresh looking and yellow; coiled fully exposed between the Philodendrum and a young palm and only a short distance in several directions from old fallen logs. Next located the 1.5m L. muta → w/ the radio, under an abandoned boardwalk plank ≈10m from the large new snake; only edge of a coil