75 



2. Two labials entering the eye ; ventrals 



182 196; subcaudals 99 III 13. T. hypomdas p. 83. 



c. Scales in 19 rows. 



1. A single anterior temporal 14. T. conspicillatus p. 83. 



2. Two anterior temporals. 



-f- Scales of outer row smooth or feebly 

 keeled; frontal one time and a half 

 to one time and three fourths as long 



as broad 15. T. trianguligerus p. 84. 



-f--f~ Scales all strongly keeled; frontal one 



time and one third as long as broad. 1 6. T. petersi p. 85. 

 B. Two or three last maxillary teeth abruptly 

 enlarged. 

 I. Scales in 1 7 rows ; three labials entering the eye. 17. T. saravaccnsis p. 85. 



II. Scales in 21 rows 18. T. chrysargoides p. 86. 



III. Scales in 19 rows. 



a. Two labials entering the eye; anal entire. 19. T. flavifrons p. 87. 



b. Three labials entering the eye; anal divided. 



1. A single anterior temporal. 



aa. Third to fifth labials entering the eye. 20. T. stolatus p. 87. 

 bb. Fourth to sixth labials entering the eye 21. T. vittatus p. 88. 



2. Two anterior temporals. 



f Internasals shorter than praefrontals ; 



scales of outer row smooth 22. T. subminiatus p. 89. 



ft Internasals as long as praefrontals; all 

 the scales strongly keeled. 



1. Subcaudals 56 94; eye large .... 23. T. chrysargus p. 89. 



2. Subcaudals 95 117; eye very large. 24. T. maculatus p. 90. 



i. Tropidonotus piscator (Schn.). 



Hydrus piscator, Schneider, Hist. Amph. I 1799, p. 247. 



Tropidonotus piscator, Boulenger, Cat. Sn. I 1893, p. 230 (s. syn.). 



Natrix piscator, Barbour, Mem. Mus. Comp. Zool. Harv. Coll. XLIV 1912, p. 109. 



Eye shorter than its distance from the nostril; latter turned 

 upwards; rostral visible from above; internasals narrowed in 

 front, as long as the praefrontals; frontal longer than its distance 

 from the end of the snout, as long as the parietals or shorter; 

 loreal about as long as deep; one prae- and three sometimes 

 four postoculars; temporals 2 + 2 or 2+3 (1+2); nine upper 

 labials, fourth or fourth and fifth entering the eye; five lower 

 labials in contact with the anterior chin-shields; latter shorter 

 than the posterior. Scales keeled, of two or three outer rows 



