A dark variety of hognose snake n (here: Heterodon platirhinos).
1743 Catesby Nat. Hist. Carolina 2.44, The black Viper. This Serpent is short and thick, of slow Motion, spreads his Head, when irritated, surprisingly broad and flat, threatning with a horrid Hiss. 1807 (1869) Pursh Jrl. Bot. Excursion 15 VA, This day I killed a monstrous large snake, which I seen likewise in Virginia, calld there Black Viper, here [=nePA] they call it blowing Atter . . they are said to be very poisenous, but on opening the mouth, I could not observe the structure of that kind in her teeth. 1868 Cedar Falls Gaz. (IA) 10 July /5 (newspaperarchive.com), The “Blue-racer,” and “Black Viper,” were among the choice varieties, and range from two to six feet in length. Several times per day the workmen would be compelled to quit work and slaughter snakes. 1882 Cambridge Jeffersonian (OH) [11 May 3]/4 (newspaperarchive.com), H. R. Lupton killed a black viper a few days ago. . . It was three feet in length. 1885 Natl. Democrat (Jeffersonville IN) 25 Sept 4/6, John Donahue, residing on the Knobs, killed the other day a black viper or blower snake which had completely swallowed, with the exception of about six inches of its tail, a slender black snake of the racer breed. 1938 Athens Messenger (OH) 31 Mar 16/8, Clarence Phillips discovered and destroyed three vipers. Two of them were spotted vipers measuring 30 inches each while the other was a black viper that was 28 inches long. 1969 DARE (Qu. P25) Inf KY11, Spreadheads—includes two species: black vipers and spotted vipers. 1972 Minton Amphibians & Reptiles IN 311, Today many people are aware of the harmless nature of this reptile and even regard it with amusement. In some districts the usual spotted phase of the species is considered harmless, but the “black vipers” or “diamondback blowing vipers” are still believed venomous.