Olaus Magnus p. 776

“There are also vipers in the northern parts…that will kill men with the sharpness of their venom in 4 hours time, unless it be stopped in time with fit remedies….Shepherds use these remedies to keep themselves safe….Serpents will raise themselves on their breasts, and go a half a cubit high, and will spit forth their venom in great quantity, and of diverse colors, that they collect in their throats, against a man that resists and comes against them: and then they will quickly run away into their holes, and under stones.”