72 COIXTBEH)^. 



posteriorly. Head distinct from neck ; eye large or rather large, 

 wiLh round pupil. Body elongate, more or less compressed ; scales 

 smooth or keeled, the laterals smaller and ohlique, with apical pits, 

 in 10 or 1 2 rows ; ventrals rounded or obtusely angulate laterally. 

 Tail long ; subcaudals in two rows. 

 Central and South America. 



Synopsis of the Species. 



I. Scales in 12 rows ; anal usually divided. 



Four or more rows of scales keeled .... 1. sexcarinatus, p. 72. 

 Scales smooth, or only the two middle 



rows keeled 2. carinatus, p. 73. 



II. Scales in 10 rows. 



Anal entire ; scales smooth, or only the 



two middle rows keeled 3. fuscus, p. 75. 



Anal divided ; scales smooth 4. melas, p. 76. 



Anal divided ; scales keeled 5. grandisquamis, p. 76. 



1. Herpetodryas sexcarinatus. 



Natrix sexcaiinata, Waffl. in Spix, Serp. Bras. p. 35, pi. xii. (1824), 



and Syst. Amph. ■$. 180 (1830). 

 ? Natrix ciniiamomea, Jf'a(/l. I. c. p. 20, pi. vi. flg. 1 

 Ei-petodryas' qiiadiiSrinatus, Boie, Isis, 1827, p. 548. 

 Herpetodryas carinatus, part., Schleg. Phys. Serp. ii. p. 175, pl.'vii. 



figs. 5-7 (1837) ; Hum. '?• Btbr. vii. p. 207 (1854) ; Jan, Icon. Gen. 



3l, pi. ii. flg. 1 (1869). 



• carinatus, Boettg. Zeitschr. f. ges. Naturw. iviii. 1885, p. 233. 



sexcarinatus, Bouleng. Proc. Zool. Soc. 1891, p. 355. 



Eye smaller than in H. carinatus. Rostral broader than deep, 

 just visible from above ; internasals as long as or a little shorter 

 than the prsefrontals ; frontal once and one third to once and two 

 thirds as long as broad, as long as or a little longer than its distance 

 from the end of the snout, a little shorter than the parietals ; loreal 

 longer than deep ; one prse- and two postoculars ; temporals 1 + 2 ; 

 eight or nine upper labials, fourth and fifth or fifth and sixth 

 entering the eye ; five lower labials in contact with the anterior 

 chin-shields, which are a little shorter than the posterior. Scales 

 in 12 rows, four or more of which are distinctly keeled. Ventrals 

 indistinctly angulate laterally, 142-159 ; anal divided (rarely 

 entire) ; subcaudals 100-128. Uniform brown or olive above and 

 on the outer ends of the ventrals ; head often reddish ; upper lip 

 and lower parts yellowish. 



Total length 1350 millim. ; tail 450. 



Venezuela, Brazil, Paraguay. 



