NATRIX 83 



Amphiesma Dumeril and Bibron, Erp. Gen. 7 (1854) 724. 

 Thaninophis Cope, Proc. Acad. Nat. Sci. Philadelphia (1860) 369. 

 Bothrodytes Cope, Proc. Am. Phil. Soc. 23 (1886) 495. 

 Ceratovhalhis COPE, Am. Nat. 27 (1893) 483. 

 Diplophallua COFE, Am. Nat. 27 (1893) 483. 



"Maxillary teeth 18 to 40, posterior longest; mandibular teeth 

 subequal. Head usually distinct from neck ; eye rather small, 

 moderate, or large, with round pupil. Body more or less elon- 

 gate, cylindrical; scales mostly keeled, in some species smooth, 

 usually with apical pits, in 15 to 33 rows; ventrals rounded. 

 Tail moderate or long ; subcaudals in two rows. Hypapophyses 

 developed throughout the vertebral column." (Boulenger.) 



This large genus is distributed over Central and North Amer- 

 ica, Europe, Asia, Africa, North Australia, the Malay Archi- 

 pelago, and Japan. 



In the Philippines seven species are known; one of these, 

 Natrix stolata (Linnai^us), reported by Peters from Calumpit, 

 Bulacan Province, Luzon, I regard as doubtful. 



Key to the Philippine species of Natrix Lazirenti. 



tt\ Maxillary teeth not more than 30, last 2 or 3 abruptly enlarged. 

 6\ Head moderately elongate; scales in 19 rows. 



c\ Single anterior temporal; third, fourth, and fifth upper labials enter- 

 ing eye; outer scale rows smooth.-.. N. stolata (Linnaeus) (p. 84). 

 c". Two anterior temporals; fourth, fifth, and sixth upper labials enter- 

 ing eye ; outer scale row feebly keeled. 



N. spilogaster (Boie) (p. 86). 

 c'. Two anterior temporals; 3 temporals entering eye; internasals as 

 long as prefrontals; outer row of scales strongly keeled. 



N. chrysarg-a (Schlegel) (p. 87). 

 b'-. Head short, very distinct from neck. 



c'. Scales in 17 rows, third, fourth, and fifth labials entering eye. 



N. auriculata (Gtinther) (p. 89). 

 c". Scales in 19 rows. 



(V. Two anterior temporals; subcaudals, 96 to 101. 



N. crebripunetata (Wiegmann) (p. 91). 

 dr. One anterior temporal; subcaudals, 64 to 71. 



N. lineata (Peters) (p. 92). 



a\ Maxillary teeth, 35 to 40; posterior but slightly enlarged; scales in 17 



or 19 rows -- .- ; N. dendropliiops Giinther (p. 95). 



The snakes of this genus, as the name suggests, are somewhat 

 aquatic ; they are usually found about moist or damp situations 

 where there are frogs, since frogs form the largest part of their 

 food. They are wholly harmless to man. Natrix spilogaster 

 is frequently captured in Manila. It is probably the best known 

 species owing to its presence about rice paddies. 



