The British Guiana Museum. 271 
snakes or those which instead of having rows of teeth in 
the maxilla, have one large fang in each, sometimes with 
one or more smaller teeth behind —the large fang, which is 
not perforated in the centre, but is grooved on one side, 
being connefted at the base with a poison-gland. From the 
fa6l that the jaws are fixed, it follows that these poison- 
ous Colubrine snakes, have the fangs permanently ereft, 
as will be seen by opening the mouth of any of the 
poisonous coral-snakes which belong to this group. The 
deadly cobras of India belong to this division. 
The Viperine snakes differ markedly from the Colu- 
brines. In them the head is short, triangular and flat, 
bearing very small, overlapping scales on the top ; and 
there is a very sudden constri6lion at the end of the 
head to form the neck. The maxilla, instead of being long 
and fixed, is short, thick and movable ; and it carries one 
long perforated poison-fang which is connected at the base 
with a poison-gland ; the poison-fang is sometimes 
followed by one or more smaller ones, the first of 
which wouldtake its place in case of accident. Thepoison- 
fangs are carried drawn up to the palate, and are ere6led 
at will, for striking, by means of muscles which move the 
jaws in which the fangs are set. These snakes all bring 
forth young alive, and are therefore stri6lly viviparous — 
hence probably the term viper ; though, from the fa£t that 
eggs are really produced and are retained in the body 
until they are hatched, the term ovo-viviparous is used 
in preference to denote this strange condition. With 
the exception of a few other forms, such as the sea- 
snakes, the other snakes are oviparous. The Crotaline 
snakes, such as the bushmaster (Lachesis mutus) of which 
some poor dried specimens alone are to be seen in the 
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