Incluye bibliografía e índice

A massive work on snakes of the four genera Agkistrodon, Calloselasma, Deinagkistrodon and Hypnale, commonly known as cantils, mamushis, copperheads, pit vipers and vipers. Work on this monograph started in the early 1930s. Gloyd had the exceptional discipline to master the detailed scale counts for more than 6200 snakes as well as the tedious labor to compile the chresonymies and the great bulk of the main bibliography of 1880 entries. Conant revised, updated, and expanded Gloyd's original text, supervised the preparation of the final distribution maps and much of the art work, assembled the hundreds of color illustrations, and attended to the myriad details involved in finalizing a complicated project such as this and seeing it through the press.