Night would soon fall, and it was then that the mountainous blasphemy lumbered upon its eldritch course. Negotium perambulans in tenebris. . . . The old librarian rehearsed the formulae he had memorised, and clutched the paper containing the alternative one he had not memorised.
H.P. Lovecraft, The Dunwich Horror
"In the entry stood the figure of a robed priest holding up a Cross, with which he faced a terrible creature like a gigantic slug, that reared itself up in front of him. "
"Below ran the legend "Negotium perambulans in tenebris" from the ninety-first Psalm. We should find it translated there, "the pestilence that walketh in darkness," which but feebly rendered the Latin."
"The Thing had entered and now was swiftly sliding across the floor towards him, like some gigantic caterpillar. A stale phosphorescent light came from it, for though the dusk had grown to blackness outside, I could see it quite distinctly in the awful light of its own presence. From it too there came an odour of corruption and decay, as from slime that has long lain below water. It seemed to have no head, but on the front of it was an orifice of puckered skin which opened and shut and slavered at the edges. It was hairless, and slug-like in shape and in texture. As it advanced its fore-part reared itself from the ground, like a snake about to strike, and it fastened on him ..."
E.F. Benson, Negotium Perambulans