THE PRINCIPAL SPECIES OF POISONOUS SNAKES 153 
curved teeth. Snout long, bearing the nostrils on its upper 
surface; head-shields large, nasals in contact with each other. 
Body rather short ; scales hexagonal or squarish, juxtaposed ; no 
distinct ventral scales. 
The principal species of this genus 
is H. platurus (syn. Pelamis bicolor, 
fig. 78). 
Coloration black or brown and 
ellow, with very variable markings. 
y j N° 2 Fic. 78.—Hydrus platurus (syn. 
Total length, 700 millimetres ; tail Pelamis bicolor). 
80. (After Kreft.) 
Habitat: Indian Ocean, Tropical 
and Sub-tropical Pacific. 
(2) Thalassophis. 
Poison-fangs followed by 5 small teeth. Snout short; nostrils 
superior, horizontal, between two nasal shields and an inter-nasal ; 
frontal and parietal shields large ; præocular present. Body rather 
elongate ; scales hexagonal, juxtaposed ; no distinct ventral scales. 
T. anomalus.—Body with dark annuli, wider on the back. 
Total length, 810 millimetres ; tail 84. 
Habitat : Java. 
(3) Acalyptophis. 
Maxillaries longer than the ectopterygoids ; frontal and parietal 
shields broken up into scales. Body rather elongate ; scales sub- 
imbricate ; no distinct ventrals. 
A. peronti.—Greyish or pale olive, with dark cross-bands ; belly 
whitish. 
Total length, 890 millimetres ; tail 115. 
Habitat: Western Tropical Pacific. 
