VIPER.INE GROUP. 
229 
to eighteen solid teeth in the maxilla, by the longer body, on the anterior part of 
which the scales are imbricating, and by the presence of more or less distinct small 
shields on the lower surface. 
Black-Banded The black-banded sea-snake (Distira cyanocincta) may be taken 
Sea-Snake. as an example of another large genus differing from the preceding in 
that the fangs are followed in the maxilla by from four to ten solid teeth with 
their front surface grooved. In these snakes the body is more or less elongated, 
and generally has the scales on its front portion slightly overlapping, while the 
under surface carries small shields. The figured species, which grows to a length 
of 6 feet, is of a greenish olive above, with black transverse bars or rings, which 
are sometimes connected by a longitudinal stripe on the under surface. This 
snake ranges from the Persian Gulf to the Malay Archipelago and Japan, and is 
one of the most abundant in the Indian seas. 
There are several points in which the sea-snakes differ from their land cousins 
as regards habits, in addition to those already noticed. In the first place, the skin 
is changed piecemeal, instead of entire; the casting taking place at very frequent 
intervals. Moreover, the tongue is very short, and only the extreme tips of its 
two extremities are exserted through small notches on either side of the rostral 
shield of the head, which is prolonged downwards so as to close the mouth. 
When, however, these snakes are cast ashore and almost blinded by the unaccus¬ 
tomed light, the tongue is used in the ordinary manner as a feeler. 
The Vipers. 
Family VlPERlDjE. 
Omitting mention of the small and unimportant family of harmless snakes 
known as blunt-heads (Amblycephalidce), represented by two Oriental and two 
tropical American genera, we pass to the viper family, which includes the 
whole of the remaining' members of the suborder. The distinction between a 
colubrine and viperine snake is that in the latter the maxillfe or hinder upper jaw¬ 
bones are capable of being erected in a vertical plane at right angles to the 
transverse bones, while in form the} 7 are short and thick, and they always carry 
a single pair of large tubular fangs. All vipers are poisonous, and, so far as 
known, produce living young; while they are more or less nocturnal and terrestrial 
in their habits, although a few ascend trees. The thick body, the flat and often 
triangular head, the short and stumpy tail, the reduction of the maxillary teeth to 
a single pair of fangs, and the vertical pupil of the eye, are all features dis¬ 
tinguishing vipers as a whole from the poisonous colubrines; but, as already 
mentioned, it is frequently necessary to examine the structure of the skull itself 
before any particular snake can be assigned to its proper serial position. That 
the vipers form a highly specialised group is self-evident; and Mr. Boulenger 
believes them to be descended from the hind-fanged colubrines. The family is 
divided into two groups, namely, the typical vipers of the Old World, which 
attain their maximum development in Africa, and the American and Asiatic 
pit-vipers. 
