Food and Food Preferences 462 MORTALITY FACTORS 465 Natural Enemies and Predators 465 Parasites and Diseases 465 Miscellaneous Causes of Death 466 BEHAVIOR 466 Annual and Diel Cycles of Activity 466 Basking 469 Coiling 469 Locomotion 470 Disposition 470 Defense and Escape 471 "Head Bobbing" 471 Combat Dance 472 THE VENOM 473 Properties of the Venom 473 Venom Yield and Toxicity 473 Susceptibility of Snakes 475 THE BITE 476 Effects of the Bite 476 Treatment 477 Case History of a Bite 479 Snakebite in the United States 480 SUMMARY 480 LITERATURE CITED 485 INTRODUCTION Objectives of the study here reported on were to: (1) learn as much as possible concerning the natural history and economic importance of the cottonmouth; (2) determine what factors limit its geographic distribution; (3) determine the role of the cottonmouth in its ecological community; and (4) compare the cottonmouth's life history with that of other crotalid snakes, especially the kinds that are most closely related to it. Twenty-five live cottonmouths were kept in the laboratory for the purpose of studying behavior and fang shedding and for comparison of measurements with those of preserved specimens. Live snakes were obtained in Brazoria and Nacogdoches counties, Texas, from Hermann Park Zoo, Houston, Texas, and from the late Paul Anderson of Independence, Missouri. Preserved western cottonmouths were examined for the purpose of determining variation, distribution, food habits, body proportions, embryonic development, and reproductive cycles. The cottonmouths examined include: 221 from Texas; 33 from Arkansas; 22 from Louisiana; 2 from Illinois; and 1 each from Kansas, Mississippi, and Oklahoma.