AIPYSURUS 225 



HYDRIN.^ 



Hydrophiinai Boulenger, Cat. Snakes Brit. Mus. 3 (1896) 264; Wall, 

 Mem. As. Soc. Bengal 2 (1907-10) 169. 



Nostrils dorsal or lateral, usually valvular; tail strongly com- 

 pressed, oarlike; hypapophyses not developed throughout the 

 vertebral column. Body compressed, the ventrals very small in 

 marine types, or large in semiaquatic forms. Rostral shield 

 with two notches in oral border; only the cleft part of tongue 

 capable of being protruded. Anterior maxillary teeth folded into 

 a tube or grooved ; frequently posterior teeth also grooved. 

 Deadly poisonous. 



Eleven genera of this subfamily are recognized; with the ex- 

 ception of Laticauda, Aipysurus, and Emydocephaliis, all are 

 entirely aquatic. The three mentioned are found frequently at 

 some distance from the water, and these genera are equipped 

 with wide ventral scales, which enable them to perform land loco- 

 motion. 



Key to the Philippine genera of the Hydrinx. 



a\ Ventral scales large, transversely widened. 



6\ Nostrils on upper surface of snout; nasals in contact. 



Aipysurus Lacepede (p. 225). 

 Ir. Nostrils lateral; nasals separated by internasals. 



Laticauda Laurenti (p. 227). 

 or. Ventral scales small or indistinguishable from body scales; nostrils 

 superior. 

 h'. All maxillary teeth grooved (sometimes faintly) ; 4 to 10 small teeth 



follow fangs..-' - Disteira Lacepede (p. 236). 



b'. Only 2 to .5 faintly grooved teeth follow the large fangs. 



Lapemis Gray (p. 249). 



h'. Poison fangs short, followed after an interspace by 7 or 8 solid 



teeth ..- --- -.. Pelamydrus Stejneger (p. 252). 



It is highly probable that species of other genera occur in the 

 Islands, and that specimens will be taken along the coasts. 



Genus AIPYSURUS Lacepede 



Aipysu7-us Lacepede, Ann. Mus. 4 (1804) 197; Dumeril and Bibron 

 Erp. Gen. 7 (1854) 1323; Fischer, Abh. Natur. Hamburg 3 (1856) 

 31; .Jan, Elenco Sist. Ofid. (1863) 108; Gunther, Kept. Brit. India 

 (1864) 357; Boulenger, Cat. Snakes Brit. Mus. 3 (1896) 303; 

 Wall, Mem. As. Soc. Bengal 2 (1907-10) 189. 



StephoMophydra Tschudi, Arch. Nat. (1837) 331; Gray, Cat. Snakes 

 (1849) 59. 



Hydrophis, part., Schlegel, Phys. Serp. 2 (1837) 488. 



Hypotropis Gray, Ann. & Mag. Nat. Hist. 18 (1846) 284. 



Tomogaster, part., Schmidt, Abh. Natur. Hamburg 2 (1852) 75. 



Emydocephalus Krefft, Proc. Zool. Soc. London (1869) 321. 



Pelagophis Peters and DORIA, Ann. Mus. Geneva 13 (1878) 413. 



161466 IB 



