insects--flies, beetles, moths, and caterpillars, though spiders are
greatly appreciated. Unless they are very small, caterpillars do not
appear to be swallowed, but rather chewed and the skin rejected. The
name _vivipara_ refers to the fact that the female retains her eggs
until they are fully developed and ready to hatch, so that the young
are born free from the egg-membrane, or the egg breaks in the act of
oviposition or immediately after. They are deposited anywhere: there is
neither nest nor concealment, and the mother exhibits no interest or
concern in her progeny. These number from six to twelve, and are nearly
black. They remain motionless where they were born for several days.
They are about an inch long. They start life so well nourished that they
take no food for several days, then start hunting for small insects,
such as Aphides and other soft-bodied species. The teeth are very small
and conical, and unfitted to deal with hard substances; and as the two
halves of the lower jaw are firmly connected there can be no distension
of the small mouth to accommodate large parcels of food, as happens with
the Snakes.
Points to be noted in the external appearance of the Common Lizard, when
we have succeeded in capturing one, are the fact that the entire body is
clothed with smooth, slightly keeled, and scarcely overlapping scales,
small on the upper side, excepting the head, where they are large. On
the underside, too, they are larger, especially from the breast to the
vent, where they become broad plates, of which there are six rows, the
two central rows being much smaller than the lateral ones. A row of
larger scales forms a sort of collar across the underside of the neck.
The Lizards have not that fixed, ever-open-eyed stare of the Snakes. The
Lizard can follow your movements with his eye, and wink at you
intelligently, because he is provided with eyelids, which the Snake
lacks. He closes his eyes in sleep. When he puts out his tongue to
ascertain whether an insect is good for food, you will notice that the
broad tip of it is notched into two rounded lobes, instead of being
forked into two thread-like points, as in the snakes. The usual
attitude of the Common Lizard is with the extended tail and greater part
of the body resting on the ground, or other support, whilst the head and
foreparts are raised on the arms, and the muzzle turned to one side in
an attitude that suggests listening. It has been stated that Lizards are
susceptible to musical sounds, and that they may be attracted from their
hiding-places by judicious whistling.
[Illustration: _Pl. 86._ _K 138._
*Sand Lizard female.*
Lacerta agilis.]
[Illustration: _Pl. 87._ _K 139._
*Common Lizard.*
Upper and under sides, showing different scaling.]
On the underside of the thighs will be found a row of small, roundish
scales, all perforated, and numbering from seven to thirteen. The
perforations are filled with a yellowish or brown substance, which
appears as a little cone above the opening. Its purpose has not been
settled satisfactorily, but Cope suggests that it may be for giving
the Lizard a better hold on slippery surfaces, seeing that the weight
of the body rests chiefly upon the thighs. Another point that should be
mentioned is the brittleness of the tail. In catching--or attempting to
catch--a Lizard, he should be grasped by the shoulders. If the tail be
held instead, it will probably come away in the hand, snapping at the
base as readily as though it were glass or sealing wax. A sort of tail
will grow from the stump if the Lizard lives long enough, but it is
always a poor, ungraceful affair.
This species is the Furze Evvet of the New Forest, and the
Harriman of Shropshire. In Cheshire it is the Swift. In suitable
situations--sandhills, fallows, heaths, and moors--it may be found all
over Great Britain, including the Isle of Man, and in most localities
it is common. It is the one true reptile that Ireland possesses,
and it appears to occur in all parts of the island, though not in
any abundance. It appears (like the Natterjack) to have escaped the
attentions of St. Patrick when "He gave the snakes and toads a twist and
banished them for ever." Its wider distribution includes Northern and
Central Europe and Siberia, where it shows a preference for mountainous
and high-lying country.
*Sand Lizard* (_Lacerta agilis_, Linn.).
At a glance there is little beyond its superior size to distinguish
the Sand Lizard from the Common Lizard; and in consequence the earlier
records of its occurrence in certain localities have had to be severely
revised. It appears to have been the rule of many recorders, when
specimens of the common species that exceeded average proportions
were captured, to put them down as Sand Lizards without any critical
examination. The truth is that as a British species the Sand Lizard is
found only in certain restricted localities in the southern counties
of Dorset, Hampshire, and Surrey, and the sandhills by the sea in
Lancashire and Cheshire. Its southern habitats agree almost exactly
with those of the Smooth Snake, for which it provides a favourite food.
It is not found either in Scotland or Ireland.
The adult male of the Sand Lizard is about seven and a half inches long,
of which more than half is tail. The female is about half an inch
longer, but the additional measure is added to the body, for the tail
is less than half of the whole length. The general colouring may be
described as a sandy-brown, with broken bands of darker tint. There is,
of course, a considerable amount of colour variation, and in the males
there is a marked tendency to a green suffusion, which in many cases is
so pronounced as to lead to a belief that the examples in question are
the non-indigenous Green Lizard (_Lacerta viridis_). It was, no doubt,
some markedly green males of the Sand Lizard which Gilbert White saw "on
a sunny sandbank, near Farnham, in Surrey," and thought were true Green
Lizards. There are rows of dark and white spots along the sides of
the back, flank, and tail, which give the appearance of longitudinal
stripes. The green of the male is more pronounced during the breeding
season (May-June) when it is also evident in the usual black-dotted
yellow of the underside. The black spots along his sides have white
centres. The under parts of the female are cream coloured, and the
three rows of white-centred spots on the sides are dark brown.
[Illustration: _Pl. 88._ _K 140._
*Sand Lizard.*
The tail, seized by an aggressor, has been parted with.]
[Illustration: _Pl. 89._ _K 141._
*Slow-worm.*
Young hatching from newly laid eggs.]
The female deposits from five to twelve--usually about eight--eggs which
have white shells of the consistency of parchment. These are covered
with sand or leaves, and left for the sun to incubate. They are laid in
July, and the young are hatched in the same month or early in August.
The young Sand Lizards are grey-brown above and whitish below.
Like the Common Lizard, the Sand Lizard is very apt to lose its tail by
voluntary amputation; and short-tailed specimens are sometimes found
which are to be explained by supposing that the original tail has been
shed and another grown.
Characters that distinguish the Sand Lizard from the common species
will also be found in the general covering of scales--which are strongly
keeled--and in the ten to eighteen on the thigh that are perforated,
which are triangular, larger and flatter than the corresponding scales
in the Common Lizard. If we have an opportunity for examining the mouth,
too, we shall find that in addition to the teeth on the jaws there is a
row of them--vomerine teeth--on the hinder part of the palate. These are
not present in the Common Lizard. Both species spend the winter in a
dormant state underground.
Outside England, the Sand Lizard is a native of Central and Northern
Europe, its range extending to the North of Russia and Siberia; but
it is a lizard of the lower lands, whilst the Common Lizard on the
Continent is more plentiful in mountain districts.
* * * * *
There are two species of Lizards that are natives of the Channel
Islands, and strangely one and not the other of these is usually
included in lists of British animals because the islands are politically
British. But the fauna and flora of the Channel Islands belong to those
of the nearest mainland--France--and therefore should not be included
among British species unless they occur also in England, Wales,
Scotland, or Ireland. The two species referred to are the Green Lizard
(_Lacerta viridis_), with tail equal to three-fourths of its entire
length, and the Wall Lizard (_Lacerta muralis_) of variable brown
coloration and a tail one and a half times the length of the head and
body. The Green Lizard may sometimes be seen in this country as an
escape from captivity, being a favourite subject with the keepers of
vivaria.
*Slow-worm* (_Anguis fragilis_, Linn.).
The average person cannot understand why the naturalist should be so
"pig-headed" as to regard the Slow-worm, Blind-worm or Deaf-adder as
a lizard when it is so obviously a snake, and has no legs such as a
properly constructed lizard should have. If the naturalist were given
to argument of the _tu quoque_ order he might retort by asking why the
average man persists in styling a swift-gliding reptile a Slow-worm,
or one with brilliant eyes a Blind-worm? But the probability is that
he will quote Longfellow and tell the inquirer that "things are not
[always] what they seem"--that under the close and polished, uniform
scaly covering there are vestiges of limbs that have been discarded in
the long evolutionary history of the species; that it has eyelids like
other lizards, that the two sides of the lower jaw have a bony union in
front, and that it has a notched not forked tongue--characters that do
not agree with the structure of any snake. But all this will fall upon
deaf ears, and the average man will go on slaughtering Slow-worms at
sight, and believing that he has done a brave and meritorious thing.
The Slow-worm attains a maximum length of seventeen or eighteen inches,
but the average "large" example is about a foot long. Its head is quite
small and short, not so broad as the body just behind it. The tail,
which is much longer than the head and body, and longer in the male
than in the female, tapers gradually, and is very slender before ending
in the short sharp point at the tip. In many examples this graceful
tapering of the tail is not evident, because at some time it has been
broken short, and the effort to renew it, whilst it gives a sort of
finish, never appears to be a success. There is usually a ragged end
to the old part, and the narrower new part appears to have been rather
clumsily stuck inside the fringe of old scales. Many specimens are in
this condition, for the Slow-worm is much more ready to part with its
tail than either of our other lizards. The scales on the upper and
under sides are nearly uniform in size and shape, broader than in the
other lizards and rounded on the hind margin which is thinner than the
dark coloured central part of the scale. The scales are quite without
keels, polished and plainly overlap their fellows. There is a thin dark
line down the centre of the back, and another on the upper part of each
side.
The small mouth has the jaws well armed with uniform slightly curved
teeth, whose points are all directed backwards. The bright eyes are
placed low down, not much above the upper jaw. The head is covered by
much larger scales than usual, but in this case the head regions are not
so clearly mapped out as in the other species, owing to the thin edges
of the scales giving no strong outlines. With a live Slow-worm in the
hand one gets a clear idea of the smoothness and close attachment of the
scaly covering. The feeling conveyed is that there are no scales: that
the external coat is continuous and homogeneous; and one marvels at
the reptile's power of gliding rapidly through the fingers. Though the
Slow-worm may be found on the edge of the wood, or on the heath, sunning
itself early in the spring, and apparently a lifeless casting in bronze,
on the slightest alarm it dives into the vegetable soil and speedily
disappears. In its basking attitude Slow-worm may be an appropriate
name; but when it begins to move we are astounded that it has been able
to keep so ridiculous a name.
The food of the Slow-worm is governed by the small size of the mouth. It
is not an easy matter to study its feeding habits when it is at large,
and our knowledge of its food preferences have been derived mainly from
Slow-worms in captivity. It will take spiders, small earthworms, and
small insects; but always shows a marked preference for the small
greyish-white slug (_Limax agrestis_) that is so great a pest to the
grower of tender vegetables. This slug the Slow-worm consumes in
quantity. Dr. Gerald Leighton, in his book on the "British Lizards,"
says: "I can vouch for a meal that consisted of seventeen slugs, the
Slow-worm being a large male sixteen inches long. But the usual number
taken seems to be from four to ten." Its principal feeding time is soon
after sunset, when the slugs are most in evidence on the surface and
beginning to make their nefarious attacks on the food of man. If the
gardener, professional and amateur, could only be taught such facts, the
sudden descent of the sharp edge of spade or hoe upon one of his ablest
helpers might be stayed. The reptiles and the batrachians are all his
friends.
Like the Common Lizard, the female Slow-worm retains her eggs until
they are fully developed, so that in August or September she produces
a litter of six to twelve animated silver needles about two inches in
length, with a thin black line along the centre of the back, and black
on the underside. These are very active and very beautiful, perfectly
independent and able to fend for themselves, catching insects, but at
once showing preference for slugs if these are to be found of a size
small enough to pass the tiny mouth. There is a record of a batch that
were three inches in length at birth, but this is unusual. Occasionally
the eggs are deposited before hatching.
Although in early spring the Slow-worm may be seen along hedgerows
frequently in the daytime, later in the year it must be sought in
the dusk when it is food-finding. It then spends the day under flat
stones and in burrows. In Cornwall years ago we could always find
a number of Slow-worms by turning over such loose stones along the
top of the cliffs; and we have since found them pretty generally
distributed without much regard to the nature of the soil. Its principal
enemies--besides man--are the Viper and the Hedgehog. In the winter the
Slow-worm retires--often in the company of half a dozen or so of its own
kind--into an underground burrow or a hollow beneath a large stone, and
goes to sleep; but it is the first of the reptiles to reappear at the
very beginning of spring. Like its congeners it casts its skin from time
to time--apparently about four times a year, but the frequency of the
sloughing depends, of course, upon whether it is a good slug year or the
reverse, for the shedding of the cuticle is in response to the demand
for more room for the growing body. The Slow-worm's length of life is
not known; but it does not appear to attain to sexual maturity until it
is four or five years of age. We have reliable knowledge of one that was
captured when about a foot in length (probably five or six years old),
fifteen years ago, which is still healthy and active.
[Illustration: _Pl. 90._ _K 144._
*Slow-worm.*
Anguis fragilis.]
[Illustration: _Pl. 91A._
*Grass Snake casts its skin.*
1. Immediately before sloughing.]
[Illustration: _Pl. 91B._
*Grass Snake casts its skin.*
2. Operation nearly complete.]
[Illustration: _Pl. 91C._
*Grass Snake casts its skin.*
3. In new attire.]
[Illustration: _Pl. 92A._
*Head of grass snake.*
A. Difference of form and scaling in heads of the two species.]
[Illustration: _Pl. 92B._
*Viper.*
B. Difference of form and scaling in heads of the two species.]
[Illustration: _Pl. 93._ _L 145._
*Grass Snake.*
Tropidonotus natrix.]
It was in the Slow-worm that the discovery was made in 1886 of vestiges
of a degenerate median eye connected with the pineal gland--a discovery
that set all the biological investigators of the world at work. The same
gland has in the last few years been found to have important influence
in controlling the growth of the body in all vertebrates.
The Slow-worm is generally distributed throughout the British Islands,
with the exception of Ireland; it is much more plentiful in the south
and south-west of England than in the east or north, but even in the
south it is much more abundant in some districts than in others. Its
wider range includes all but the extreme north of Europe, Western Asia,
and Algeria.
SNAKES
*Grass Snake* (_Tropidonotus natrix_, Linn.).
Before entering upon a description of the greatly feared though harmless
Grass, Ringed, or Common Snake, it would be well to say a few words on
the structure of Snakes in general, and so avoid some amount of
repetition, for in a general way our three species are alike.
The Slow-worm, our legless Lizard, affords a convenient transition
to the Snakes; but the bony skeletons of Snake and Slow-worm exhibit
considerable differences. No Snake possesses a breastbone, bladebone,
or collarbone, so that all the ribs are free at their ends, and they
are strongly curved to produce the cylindrical form of body. When bulky
food is taken the ribs can be flattened out to allow of the necessary
distension of the body until digestion and muscular pressure have
reduced the bulk. The bones of the skull are connected so loosely that
the head can be flattened and widened, so that the mouth can admit
prey equal to three times the size of the Snake's head under normal
conditions. To assist in the swallowing of such large bodies, the two
halves of the lower jaw have no bony connection but are united instead
by elastic ligaments, so that each half can be moved independently of
the other, and by the alternate movement of the two sides with the teeth
all pointing backwards the food is worked back to the throat. There are
other teeth on the roof of the mouth which make it difficult for living
prey to struggle forward and escape when once it has been seized. The
teeth are all thinly coated with enamel, and are not planted in sockets.
If they should get broken by the severe work imposed upon them, they
are soon replaced by others which lie in reserve. Poison fangs are much
larger than ordinary teeth, and the enamel is folded so as to produce a
groove down which poison is pressed from a gland into the wound made by
the point of the fang. The fang is hinged at its base and ordinarily
lies pressed back upon the upper jaw, and is only "erected" when the
Snake is prepared to strike.
[Illustration: *The Head Shields of a Snake.*
_r_, rostral shield;
_ff_, anterior and posterior frontal;
_v_, interparietal;
_s_, supraocular;
_o_, parietal;
_nn'_, nasal;
_l_, loreal;
_a_, preocular;
_p_, postocular;
_uu_, upper labial;
_tt'_, temporal;
_m_, mental;
**, lower labial;
_cc_, chin-shields.--After Günther.]
Externally the Snake is covered by small overlapping scales on the upper
parts and by broad plates on the under surface. The head is covered
mainly by shields, each of which has a definite name, but for the
purposes of this book it is not necessary to enter upon a tedious
recital of these terms, beyond giving them for reference under the
diagram of a Snake's head.
[Illustration: *Skeleton of Snake.*]
The eyes of a Snake are always wide open, for there are no movable
eyelids to close them. The eyeball has slight power of movement under
its transparent cover, which protects it much as the watch-glass
protects the delicate hands of the watch. As in the Slow-worm, there
is no external indication of ears, though these are present under the
scales. The very long and slender tongue divides forwards into two
branches, and when not in use is drawn into a sheath at its base. It is
constantly used to ascertain the nature of things by contact, and for
this purpose is protruded through a little gap in the front of the upper
jaw. The gape of the mouth extends far beyond the eye. The forward
extremity (_glottis_) of the wind-pipe can be thrust outside the mouth
when, owing to the passage of a bulky victim, there is danger of
obstruction by compression.
The British Snakes represent the two families Colubridæ and Viperidæ.
* * * * *
Every summer and autumn our daily newspapers afford evidence that on
the subject of Snakes the average man has not advanced in knowledge
beyond that of his prototype a thousand years or so back. With all that
has been done in various ways during the last half-century to spread
knowledge of natural things, it is astonishing that editors should admit
scare reports about Snakes without a line to set the reader right.
Internal evidence shows that nine-tenths of these alarming reports about
poisonous and aggressive Snakes refer to the innocuous Grass Snake. This
is the kind of thing that reflects the vaunted intelligence and calmness
of the average Briton:--
"An enormous snake was killed yesterday at ----, only a few yards from
where some children were playing. The Rev. Mr. Blank courageously seized
the reptile behind the head, but when it hissed savagely at him he was
forced to throw it down. Its head was then smashed with a pole, and
finally it was despatched with the aid of a spade. The venomous monster
was found to be over three feet in length. Its nest was found and a
large number of eggs destroyed."
[Illustration: _Pl. 94._ _L 148._
*Vipers.*
The two sexes: the lower figure is the male.]
[Illustration: _Pl. 95._ _L 149._
*Smooth Snake.*
Coronella austriaca.]
A very elementary knowledge of our native snakes--such as all country
folk might be expected to possess--would dispose of all this fear and
sensation, for no one has ever found a Viper or Adder--our only venomous
snake--that measured quite as much as three feet, or that had a nest of
eggs.
* * * * *
The Grass Snake is our largest British species, full-grown females
averaging four feet in length; the males a foot less. Exceptional
examples are little short of six feet, and in Italy the same species
attains to a length of eight feet. It is of graceful form, the body
tapering gently from its middle to the very slender tip of the tail. The
long, narrow head, covered with large shields, ends in a blunt snout,
with eyes and nostrils at the sides. The rather large eyes have round
pupils circled with gold and a dark brown iris. Just behind the head
there are two patches of yellow or orange (sometimes white) forming a
bright collar which serves to indicate this species at a glance. In
large females this collar is sometimes missing. Immediately behind it
are two patches of black, often united in the middle line, and behind
these the ground colour of grey, olive, or brown is uniform to the tip
of the tail. Upon the ground colour of the back are laid two rows of
small blackish spots, and a row of short vertical bars along each side.
The underside, which is covered with broad plates, is chequered in black
and white (or grey); but is sometimes entirely black. The tail accounts
for about one-fifth only of the total length.
Apart from the head-shields and the broad plates of the underside,
the Grass Snake is covered with nineteen rows of small, overlapping,
lance-shaped scales with a central ridge or "keel." These scales are an
outgrowth from the skin, and when the Snake moults they do not fall off
as the hairs of fur-clad animals do, but the entire skin with its scales
is cast intact. It separates first at the edges of the jaws, and the
Snake pushes against the ground, stones, or plant stems until the loose
skin is behind the head. Then it glides out of the remainder, reversing
it in the process. In these discarded sloughs the lens-like covering of
the eye will be found unbroken.