634 REPTILIA, 
is much elongated; the kidneys are not opposite one 
another. 
The poison is useful in defence, and in killing the prey, 
which is always swallowed whole. It is interesting to notice 
a recent discovery, requiring amplification, that the bile of 
a poisonous snake is an antidote to its venom. 
The British adder (Peas berus) is viviparous, and so are a few 
others. The great majority are oviparous, but confinement and 
abnormal conditions may make oviparous forms, like the Boa con- 
strictor and the British grass-snake (7vopedonotus natrix), viviparous. 
The female python incubates its eggs. 
Many Ophidians become lethargic during extremes of temperature, 
or after a heavy meal. 
Snakes are especially abundant in the tropics, but occur in most 
parts of the world. They are absent from many islands; thus there 
are none in New Zealand, and we all know that there are no snakes 
in Iceland. Most are terrestrial, but not a few readily take to the 
water, and there are many habitual sea-serpents. 
The serpent still bites the heel of progressive man, the number of 
deaths from snake-bite in India alone amounting to many thousands 
yearly. 
True Ophidians first occur in Tertiary strata. 
Some Examples of Ophidia 
Typhlopide. The lowest and most divergent Ophidians, occurring 
in most of the warmer parts of the earth, generally smaller than 
earthworms, usually subterranean burrowers, with eyes hidden 
under scales, with a non-distensible mouth, with teeth restricted 
either to the upper or to the lower jaw. ‘‘The palatine bones 
meet, or nearly meet, in the base of the skull, and their long axes 
are transverse ; there is no transverse bone; the pterygoids are not - 
connected with the quadrates.” The quadrate articulates with the 
pro-otic, for there is no squamosal. 
Example.— 7yphlops, very widely distributed. 
In other Ophidians the palatines are widely separated, and their 
long axes are longitudinal ; there are transverse bones connecting 
palatines and maxille; the pterygoids are connected with the 
quadrates. 
In innocuous snakes the poison gland is not developed as such; the 
maxillary teeth are not grooved. 
Examples.—The British smooth snake (Coronel/la levis); the 
British grass-snake (Zropidonotus natrix); the Pythons ; 
the Boas, of which the Anaconda (Boa murina) (30 feet) is 
the largest living Ophidian. 
In venomous snakes some of the maxillary teeth are grooved, and in 
the most venomous the groove becomes a canal open at both ends, ' 
