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The checkered keelback or Asiatic water snake (''Xenochrophis piscator'') is a common species of nonvenomous snake found in Asia. ==Description== This snake's eyes are rather small, and shorter than its distance from the nostril in the adult. Its rostral scale is visible from above. The internasal scales are much narrowed anteriorly and subtriangular, with the anterior angle truncated and as long as the prefrontal scales. The frontal scale is longer than its distance from the end of the snout, and as long as the parietals or a little shorter. The loreal is nearly as long as it is deep. There is one preocular and three (rarely four) post-oculars. Its temporals are 2+2 or 2+3. There are normally nine upper labials, with the fourth and fifth entering the eye and five lower labials in contact with the anterior chin-shields, which are shorter than the posterior. Scales are arranged in 19 rows, strongly keeled, with outer rows smooth. Ventrals are at 125–158, anal divided, with subcaudals at 64–90. Coloration is very variable, consisting of dark spots arranged quincuncially and often separated by a whitish network, or of black longitudinal bands on a pale ground, or of dark cross bands, with or without whitish spots. Two oblique black streaks, one below and the other behind the eye, are nearly constant, lower parts white, with or without black margins to the shields.〔Boulenger, G.A. (1890) Fauna of British India. Reptilia and Batrachia.〕 A rare case of autotomy is reported from Vietnam.〔 N. B. Ananjeva and N. L. Orlov 1994. "Caudal Autotomy in Colubrid Snake ''Xenochrophis piscator'' From Vietnam" ''Russian Journal of Herpetology'' 1(2)〕 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「Checkered keelback」の詳細全文を読む スポンサード リンク
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