black stripe that starts at the neck and runs down to the tail tip. Aberrant specimens, described by Lema (1960, 1987), had dark dorsal stripes running down the length of the body. Common namesUrutu, wutu, crossed pit viper. The common names urutu and wutu refer to the crescent markings on the body. In Argentina, it is referred to as víbora de la cruz and yarará grande. In Brazil it is called boicoatiara, boicotiara (Tupi dialect), coatiara, cotiara (southern Brazil), cruzeira, cruzeiro, jararaca de agosto (Rio Grande do Sul, Lagoa dos Patos region), jararaca rabo-de-porco (Rio Grande do Sul), and urutu. In Paraguay it is called mbói-cuatiá, mbói-kwatiara (Gí dialect), and yarará acácusú (Guaraní dialect). In Uruguay it is referred to as crucera, víbora de la cruz and yarará. Geographic range Found in southeastern Brazil, Paraguay, Uruguay and northern Argentina. In Argentina it is found in the provinces of Buenos Aires, Catamarca, Córdoba, Corrientes, Chaco, Entre Ríos, Formosa, La Pampa, Misiones, San Luis, Santa Fe, Santiago del Estero and Tucumán. The type locality is listed as "Amérique méridionale" and "Paraguay." Habitat Occurs in tropical and semitropical forests, as well as temperate deciduous forests. According to Gallardo (1977), it prefers marshes, low-lying swamps, riparian zones and other humid habitats. It is also said to be common in sugarcane plantations. It is found in a variety of habitats depending on the latitude, including open fields and rocky areas in the Sierra de Achiras in Córdoba and the Sierra de la Ventana in Buenos Aires in Argentina, fluvial areas, grasslands and cerrado. However, it is usually absent in dry environments. Reproduction Females, depending on their size, give birth to varying numbers of live young. Leitão de Araujo and Ely (1980) reported on two litters that had average weights of and and average total lengths of and , with captive females giving birth to 3-12 young. Cardinale and Avila (1997) collected one female in 1995 that was found to contain 26 embryos. Haller and Martins (1999) determined that the species produces 1-24 offspring at a time. Neonates are identical to the adults, except that they are more brightly colored. Neonates are capable of a venomous strike immediately when they are born. Venom An important cause of snakebite within its range, bites are rarely fatal but frequently cause severe local tissue damage. Although Spix and Martius (1824) found that it had a reputation for being one