Gaboon Puff Adder. The Gaboon Puff Adder takes its name from the river Gabun, a tributary of the Congo. Ex-president Roosevelt and party expect to spend considerable time in the regions where these snakes abound. The Puff Adder hisses with a puffing sound. It has an unusually broad triangular head, due to the excessive size of its poison sacs. Its bite is very deadly, being perhaps the most quickly fatal of any serpent known, and it is very ugly in appearance. It attains a length of four or five feet, and is often as thick as a man's arm. In color it is yellowish brown checkered with reddish brown and white.