4. TROPIDONOTUS TESSELLATUS, Laurenti (_Coluber hydrus_, Pallas) The Tessellated Water-Snake _Form._--Rather slender; head rather long and narrow; snout obtuse, not prominent; eyes and nostrils directed upwards and outwards, the former rather small, the latter somewhat valvular. Tail four to six times in the total length. _PLATE III_ [Illustration: TROPIDONOTUS TESSELLATUS] [Illustration: TROPIDONOTUS VIPERINUS _After Sordelli_] [Illustration: T. VIPERINUS, VAR. AUROLINEATUS _After Sordelli_] _Head-Shields._--Rostral broader than deep, visible from above. Nasal often semidivided. Internasals usually as long as broad or longer, subtriangular, truncate in front, as long or nearly as long as the prefrontals. Frontal a little broader than the supraocular, once and a half to twice as long as broad, as long as or a little shorter than its distance from the end of the snout, shorter than the parietals, not in contact with the preocular. Loreal as deep as or deeper than long. Two (rarely one or three) preoculars, with or without a small subocular below; three postoculars, often with one or two suboculars below. Temporals 1 + 2. Upper labials eight (rarely seven, nine, or ten), fourth or fourth and fifth (rarely third or fifth) entering the eye. Five (rarely four) lower labials in contact with the anterior chin-shields, which are shorter than the posterior. [Illustration: FIG. 17] _Scales_ with two apical pits, in nineteen rows, strongly keeled, of outer row smooth or feebly keeled. Ventrals 160 to 187; anal divided; subcaudals 48 to 79. _Coloration._--Olive, olive-grey, or brown above, with dark spots usually arranged quincuncially or forming narrow bars on the back (Plate III.); sides often with lighter vertical bars; a more or less distinct [V]-shaped dark band on the nape, sometimes produced as a median streak to the frontal shield; upper lip yellowish, with dark bars on the sutures between the shields. Lower parts whitish, yellow, orange, or red, marbled or checkered with black, or nearly entirely black. Iris golden, bronzy, or coppery red.