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SNAKES. 
( P. colubrinus), with the same distribution, is distinguished by the presence of an 
unpaired shield on the head, and the arrangement of the scales in from twenty-one 
to twenty-five rows; while the third species (P. schistorhynchus), from the China 
Sea and Western Pacific, differs in having a keel along the hinder half of the 
lower surface of the body. That the broad-tailed sea-snakes are the direct 
descendants of terrestrial forms allied to the craits, is proved by their retention of 
large inferior shields, and by their habits. Not only are these snakes frequently 
found at some distance from water, but in Sumatra a specimen was captured 
nearly a day’s march inland. 
Parti-Coloured In common with all the other members of the subfamily, the 
sea-snake, parti-coloured sea-snake (Hydrus platyurus) has the nostrils placed 
on the upper surface of the muzzle; and the under surface of the body and tail 
BLACK-BANDED SEA-SNAKE (f nat. size). 
in this species are scaled like the rest, although in some of the genera traces of 
enlarged shields still persist. In the skull, the maxilla is considerably longer than 
the transverse bone, and carries a pair of short fangs, followed, after an interval, 
by seven or eight solid teeth; the muzzle is elongated ; the head-shields are large, 
the nasals being in contact with one another; and the scales on the relatively 
short body hexagonal in form and with their edges in apposition. This snake 
attains a length of a yard; and in colour is either yellowish with symmetrical 
black transverse bands or spots, or uniformly black above, and yellow, with or 
without black spots below; the yellow tail being ornamented with either black 
spots or bars. It is the sole representative of its genus, and has a wider dis¬ 
tribution than any other member of the group, ranging over the whole of the 
Indian Ocean and the tropical and subtropical portions of the Pacific. The 
tpyical sea-snakes, forming the large genus Hydrophis , differ in having from seven 
