Either of two species of pit viper: the water moccasin or the Mexican moccasin (Agkistrodon bilineatus). The Mexican moccasin, or cantil, is a dangerous snake of lowland regions from the Rio Grande to Nicaragua. About 3 ft (1 m) long, it is brown or black with narrow, irregular, whitish bars on its back and sides. Seealso copperhead.
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