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''Bitis'' is a genus of venomous vipers found in Africa and the southern Arabian Peninsula.〔 It includes the largest and the smallest vipers in the world. Members are known for their characteristic threat displays that involve inflating and deflating their bodies while hissing and puffing loudly.〔 The type species for this genus is ''B. arietans'',〔 which is also the most widely distributed viper in Africa.〔 Currently, 14 species are recognized. Members of the genus are commonly known as African adders,〔Mallow D, Ludwig D, Nilson G. 2003. ''True Vipers: Natural History and Toxinology of Old World Vipers''. Malabar, Florida: Krieger Publishing Company. 359 pp. ISBN 0-89464-877-2.〕 African vipers,〔Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Dubai: Ralph Curtis Books. Oriental Press. 192 pp. ISBN 0-88359-029-8.〕 or puff adders. ==Description== Size variation within this genus is extreme, ranging from the very small ''B. schneideri'', which grows to a maximum of and is perhaps the world's smallest viperid, to the very large ''B. gabonica'', which can attain a length of over and is the heaviest viper in the world.〔 All have a wide, triangular head with a rounded snout, distinct from the neck, and covered in small, keeled, imbricate scales. The canthus is also distinct. A number of species have enlarged rostral or supraorbital scales that resemble horns. Their eyes are relatively small. They have large nostrils that are directed outwards and/or upwards. Up to six rows of small scales separate the rostral and nasal scales. All species have a well-developed supranasal sac. The fronts of the maxillary bones are very short, supporting only one pair of recurved fangs.〔〔U.S. Navy. 1965. ''Poisonous Snakes of the World''. Washington, District of Columbia: United States Government Printing Office. 212 pp.〕 These snakes are moderately to extremely stout. Their bodies are covered with keeled scales that are imbricate with apical pits. At midbody, the dorsal scales number 21-46. Laterally, the dorsal scales may be slightly oblique. The ventral scales, which number 112-153, are large, rounded and sometimes have slight lateral keels. Their tails are short. The anal scale is single. The paired subcaudal scales number 16-37 and are sometimes keeled laterally.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bitis」の詳細全文を読む スポンサード リンク
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