New Guinea .......... _Batrachopsis_.
β. Sacral vertebra with two condyles.
India and Malaya .......... _Leptobrachium_, p. 166.
_b._ Vertebrae opisthocoelous.
Ceylon and Malayan Islands .......... _Megalophrys_, p. 60 (Fig. 11).
New Guinea .......... _Asterophrys_.
{162}_Pelobates_ ("Spade-foot").–The tympanum is absent; the toes are
webbed. The inner tarsal tubercle is large, and is transformed into a
shovel which is covered with a hard, sharp-edged, horny sheath. The skin of
the upper surface of the head is partly co-ossified with the underlying
cranial bones, giving them a pitted appearance. The general shape is
toad-like.
_P. fuscus._–The smooth skin is brown above, with darker marblings, while
the under parts are whitish, but the coloration varies greatly, from pale
to dark brown or olive-grey with more or less prominent irregular dark,
sometimes confluent, patches. Some specimens are adorned with numerous red
spots. The tarsal spur is yellow or light brown. The iris is metallic red
or golden. The male has a long oval gland on the upper surface of the upper
arm, and although possessed of a voice, has no vocal sacs. The total length
of full-grown females is nearly 3 inches, that of males half an inch less.
The "Spade-footed Toad," which occurs throughout the whole of Central
Europe, extends from Belgium and the middle of France to North-Western
Persia, and from the southern end of Sweden to Northern Italy. It prefers
sandy localities, in order to dig its deep hole, in which it sits concealed
during the daytime. Owing to the looseness of the sand, the hole is filled
up so that no trace of its inhabitant is left. The digging is done by means
of the spades, and in suitable localities the animal soon vanishes, sinking
backwards out of sight. Except in the breeding season, or at night, it is
therefore found only accidentally. The sand-loving habits do not, however,
prevent it from enjoying moist localities. Several which I have kept for
years dig themselves into the wettest moss in preference to the drier parts
of their habitation. Being thoroughly nocturnal, they hunt after nightfall,
the food consisting of all sorts of insects and of worms. When captured
they utter a startling shrill cry, and their skin becomes covered with a
dermal secretion which smells like garlic, a peculiarity which has given
them in Germany the name of "Knoblauchskröte," "garlic-toad." Although they
become very tame, so that they no longer smell when handled, they can be
made ill-tempered by being pinched or otherwise teased, whereupon they take
up a defiant attitude, and with open mouth continue to cry for several
minutes. Some such scenes occur now and then, without {163}my interference,
with the specimens which share their abode with several species of
_Amblystoma_ and _Spelerpes_; there are heard now and then sudden loud
yells, like the squeak of a cat or the yapping of a little dog.
In the spring the Spade-footed Toads take to the water for about a week,
and the male's call-note is an ever-repeated clucking sound, which can also
be produced under water, with the mouth shut, the air being shifted
backwards and forwards through the larynx. The male grasps his mate below
the waist; the eggs are combined into one thick string, which is about 18
inches long, and is wound round and between the leaves and stalks of
water-plants. The eggs measure 2-2.5 mm., and are very numerous, a large
string containing several thousands. The larvae are hatched on the fifth or
sixth day in a very unripe condition. They are only 4 mm. long, quite
black, and still devoid of gills and tail. They attach themselves to the
empty gelatinous egg-membranes, which they possibly live upon. On the
following day the tail begins to grow; two days later fringed external
gills sprout out and serve for about ten days, when they in turn give way
to new, inner gills. The little tadpoles then leave their moorings and
become independent. The hind-limbs appear in the ninth week, the fore-limbs
in the twelfth. At the age of three months they begin to leave the water.
The most remarkable feature is the enormous size of the full-grown tadpole,
the body of which is as large as a pigeon's egg; the usual total length,
including the tail, amounts to about 4 inches or 100 mm., but occasionally
regular monsters are found. This was the case some thirty years ago, when
the Berlin Museum received a number of tadpoles, the largest of which
measured nearly 7 inches. They were found in the month of December near
Berlin, in a deep clay-pit with high, steep walls, so that the tadpoles
were prevented from leaving the water. Similarly hemmed-in broods probably
hibernate in the water under the ice, and such instances have been
recorded. Normally they metamorphose into the much smaller toad within the
same year.
_P. cultripes._–This is the Spade-foot of the whole of Spain and Portugal
and of the southern and western parts of France. It is similar in habits to
_P. fuscus_, from which it differs but slightly. The tarsal spur is black,
and there is a parieto-squamosal bridge which completely roofs over the
temporal fossa {164}and closes the orbit behind.–Boulenger has discovered
the rare, individual occurrence of minute teeth on the parasphenoid and on
the pterygoids of this species. These teeth are unquestionably the last
reminiscences of a condition almost entirely superseded in the recent
Anura.
_P. syriacus_ from Asia Minor and Syria agrees with _P. cultripes_ in the
cranial configuration, but has the yellow or brown spur of _P. fuscus_.
[Illustration: FIG. 33.–_Pelobates cultripes_, Spade-foot Toad, × 1, and
under surface of left foot.]
_Scaphiopus._–The Spade-foot of North America and Mexico differs slightly
from those of Europe, chiefly by the presence of a more or less hidden
tympanum and of a subgular vocal sac, and by the sternum, which forms an
entirely cartilaginous plate without a special style. The close
relationship of these two genera is further indicated by the occurrence of
peculiar large glandular complexes in some of the species, pectoral in _S.
solitarius_, tibial in _S. multiplicatus_ of Mexico. At the same time this
genus approaches _Pelodytes_.–About eight species are known, two of which
inhabit the United States, the others Mexico.
{165}_S. solitarius_ is the commonest species of the Southern States. It is
brown above, with darker patches; its total length is about 2 inches.
According to Holbrook it excavates small holes half a foot deep, in which
it resides, seizing upon such unwary insects as may enter its dwelling. It
never leaves the hole except in the evening or after long-continued rains.
It appears early in March, and soon pairs; as an instance of hardiness
Holbrook mentions that he has met it whilst there was still snow on the
ground. When teased they assume a humble attitude, bending the head
downwards with their eyes shut, as illustrated by Boulenger.[78]
_Pelodytes_ is, like the rest of the genera, devoid of the tarsal digging
spur. The tympanic disc is rather indistinct; the male has a subgular sac.
The general appearance of the slender body with long hind-limbs and toes is
frog-like. Two species only are known, one in South-Western Europe, the
other in the Caucasus.
_P. punctatus._–The "Mud-diver" has the upper parts covered with small
warts, and is about 1½ inch in length. Its coloration is variable, and
changes much. One day it may appear greenish brown, the next day pale grey;
in the daytime perhaps with many bright green spots, and in the evening
spotless and unicoloured. The under parts are mostly white, sometimes with
a fleshy tinge. The male has a voice like "kerr-kerr" or "creck-creck,"
uttered during the breeding season, which lasts from the end of February
until May, according to the temperature and the more Southern or Northern
locality. Occasionally they breed a second time in the summer or autumn.
The male develops nuptial excrescences, chiefly three rough patches on the
inner side of the fore-limbs or on the inner side of the first two fingers,
while the belly and thighs are covered with small granules. In the mode of
copulation, the laying of the small and numerous eggs, the hatching of the
larvae in a tail- and gill-less condition, this genus closely resembles
_Pelobates_; but the tadpoles never reach a colossal size, the usual length
being 2 inches, and even this is comparatively large for so small a
species. It inhabits the greater part of France, most of Portugal, and the
southern half of Spain, avoiding, however, the central plateaux and the
mountain-ranges. Its habits are essentially nocturnal, {166}living in the
immediate vicinity of the water, into which it hops with a long jump in
order to hide in the mud. Easily kept, it breeds regularly in captivity,
according to circumstances at almost any time of the year.
_P. caucasicus_ has been discovered in the Caucasus at an altitude of 7000
feet. The remaining genera of this family contain only a few species each,
and are restricted to South-Western Asia, the Malay and Papuan Islands. The
commonest is _Leptobrachium_, which ranges from the Himalayas to Borneo and
Java. Pupil vertical. Vomerine teeth sometimes absent. Tongue roundish,
very slightly nicked behind. Tympanum indistinct. Omosternum small,
cartilaginous. Male with internal vocal sacs. Tarsus with a roundish
tubercle. Some of the species, e.g. _L. carinense_ from the Karen Hills,
attain to a large size, namely, 6 inches; they seem to live on rats and
mice, and one specimen contained a young squirrel.
FAM. 3. BUFONIDAE (Toads).–The formula:–no teeth in the upper and lower
jaws, vertebrae procoelous and without ribs, sacral diapophyses dilated,–is
sufficiently diagnostic of this cosmopolitan family. The generally
entertained notion that toads have a rather thick-set, short-limbed, warty
appearance, does not apply to all the members of the family. The majority
are quite terrestrial, many are burrowing, the Javanese _Nectes_ is
aquatic, the Afro-Indian _Nectophryne_ is arboreal, while the Australian
_Myobatrachus_ and the Mexican _Rhinophrynus_ eat termites and are
correspondingly modified; lastly, _Bufo jerboa_ is a slender, long-legged
creature.
Teeth are almost entirely absent, except in _Notaden_, which has teeth on
the vomers. The omosternum is mostly absent, except in _Engystomops_ and in
some species of _Bufo_, while in _Notaden_ it is merely vestigial. The
metasternum shows more variety. The tympanum is usually distinct, but
varies even within the same genus, being hidden beneath the skin or being
entirely absent. The terminal phalanges are modified according to the
habits of the species, but they are never claw-shaped.
The Bufonidae are connected in various directions. The Neotropical
_Engystomops_ greatly resembles the likewise Neotropical Cystignathoid
_Paludicola_, and the Australian _Pseudophryne_ closely approaches the
Australian Cystignathoid _Crinia_. It is therefore all the more remarkable
that a similar approach, in another direction, namely, towards the
Firmisternal family of the {167}Engystomatidae, is indicated by the Mexican
_Rhinophrys_ and the Australian _Myobatrachus_. However, since there are no
true Engystomatidae in Australia, although several genera occur in
Papuasia, these cases may be instances of convergence without necessarily
implying relationship. An unmistakable line of connexion leads, according
to Boulenger, to the Pelobatidae, the link being the Himalayan
_Cophophryne_, with very strongly dilated sacral diapophyses, with a single
condylar articulation of the coccyx with the sacral vertebra (as in some
Indo-Malayan Pelobatidae), while this articulation is bicondylar in all the
other Bufonidae.
[Illustration: FIG. 34.–Map showing distribution of Bufonidae. The vertical
lines indicate the occurrence of Bufonidae, but not of _Bufo_.]
The whole family is divided into nine genera with more than a hundred
species, of which only about fifteen do not belong to the genus _Bufo_. The
distribution of the family is well-nigh cosmopolitan, with the remarkable
exception of Madagascar, Papuasia, and the small islands of the Pacific;
_Bufo_ has been wrongly said to inhabit the Sandwich Islands. The greatest
number of species, chiefly _Bufo_, occur in the Neotropical region, the
greatest number of genera in Central America, where _Bufo_ is rare, and in
Australia, where it is absent.
A. Pupils contracted to a horizontal slit. Typically arciferous.
_a._ Australian. Tympanum invisible. Fingers and toes not dilated.
1. With vomerine teeth. Both the omo- and meta-sternum are
rudimentary. East Australia: .......... _Notaden bennetti_.
2. Without vomerine teeth. Omosternum absent. Metasternum
cartilaginous: .......... _Pseudophryne_, p. 168.
{168}_b._ Not Australian.
1. Omosternum narrow and cartilaginous. Metasternum with a bony style
ending in a cartilaginous disc. Fingers and toes slightly swollen.
Neotropical: .......... _Engystomops_, p. 168.
2. Omosternum absent. Metasternum cartilaginous.
α. Fingers and toes webbed; terminal phalanges T-shaped and with
adhesive broadened tips. Africa and India: ..........
_Nectophryne_, p. 169.
β. Fingers free, toes webbed; terminal phalanges simple, not
dilated. Tympanum distinct. Java: .......... _Nectes_, p. 169.
3. Metasternum cartilaginous, sometimes ossified along the middle.
Fingers free; toes more or less webbed; tips simple or dilated into
very small discs: .......... _Bufo_, p. 169.
B. Pupil a vertical slit. The epicoracoid cartilages are narrow and
scarcely overlap. Omosternum absent except in _Cophophryne_. Vomerine
teeth absent. Sacral diapophyses strongly dilated. The terminal phalanges
are simple and the tips are pointed.
_a._ Australian. Tympanum distinct. The metasternum is calcified
along the middle: .......... _Myobatrachus_, p. 184.
_b._ Mexican. Tympanum absent. Metasternum rudimentary: ..........
_Rhinophrynus_, p. 185.
_c._ Himalayan. Tympanum absent. Metasternum with a slender bony style:
.......... _Cophophryne sikkimensis_.
_Engystomops_ is interesting because it closely resembles the Cystignathoid
genus _Paludicola_, and thereby seems to connect these two families. It
differs from _Paludicola_ chiefly by the absence of teeth, by the
moderately dilated sacral diapophyses and by the slightly swollen tips of
the fingers and toes, the end-phalanges of which are, in one species, _E.
petersi_, T- or anchor-shaped The tympanic disc is either distinct or
hidden. The males have a large subgular vocal sac. The generic name refers
to the small head with a prominent snout. Three species are known from
Central America and Ecuador.
_Pseudophryne_ appears to be another link with the Cystignathidae by its
resemblance to the Australian genus _Crinia_, from which it differs by the
absence of teeth and by the absence of an omosternum. The sacral
diapophyses are but moderately dilated. The males have a flat oval gland on
the hinder side of the thighs, and they are provided with a subgular vocal
sac. The 3 or 4 species of this genus which live in Australia, both East
and West, are not unlike _Bombinator_ in their general shape, short limbs
and coloration. The skin of _P. australis_ and _P. bibroni_ is covered with
small smooth warts and is blackish brown, while the under parts are
blackish with large yellow {169}patches. Total length little more than one
inch. Concerning the breeding habits, see p. 223.
_Nectophryne._–The sacral diapophyses are strongly dilated. _N. afra_,
without a tympanum, but with fully-webbed digits and several broad,
cushion-like or lamellar pads on the fingers and toes, inhabits the
Cameroons, _N. tuberculosa_ of Malabar, and _N. guentheri_ and _N. hosei_
of Borneo, have a visible tympanum and the fingers are webbed at the base
only. These slender and long-legged species are most probably arboreal, as
indicated by the broadened, but truncated, tips of their fingers and toes.
_N. hosei_ is about 4 inches long, _N. misera_ is a little creature of only
¾ inch in length. _Nectes_, hitherto known by one species, _N. subasper_ of
Java, is a swimmer and exceeds 6 inches in length. The tympanum is very
distinct; the small nostrils look upwards. The toes are long and webbed to
the tips; the hind-limbs are very long. The sacral diapophyses are strongly
dilated. The skin of the upper parts is very rugose, covered with round
warts, and dark brown; the under parts are granular and uniformly light
brown.
_Bufo._–The great number of species, more than 100, renders a strict
definition of this genus difficult. The tongue is pear-shaped, thicker in
front, entire, not cut out, but free behind, so that it can be projected.
The fingers are free, the toes more or less webbed although never
completely so. The terminal phalanges are obtuse and sometimes carry tiny
discs. The omosternum is absent or merely vestigial. The metasternum is a
rather large cartilaginous plate with a waist, which is sometimes
incompletely calcified. The sacral diapophyses are moderately dilated. The
tympanum is distinct or hidden. The skin of the upper parts is always rich
in specific poison-glands, a concentration of which forms in many species
very conspicuous, thickened parotoid glands. The surface of the skin may be
smooth, moist and slimy, or rough and warty, sometimes covered with tiny,
sharp, horny spikes and quite dry.
The genus is cosmopolitan, with the exception of the whole Australian
region and Madagascar, from which we may perhaps conclude that its original
centre was not in Notogaea, in spite of the diversity of species in the
Neotropical region, which now contains about half of all the species known.
Next to Central America the Indian region is richest in species of _Bufo_.
{170}_B. vulgaris._–The Common Toad of the Palaearctic region. The skin of
the upper parts is much wrinkled and beset with numerous round warts or
poison-glands, the openings of which can be seen with the naked eye,
especially on the large parotoid complexes. The outermost layer of the
epiderm, in fact all that portion which is periodically shed, is elevated
into numerous little cornified spines. The extent of their development
varies much; southern specimens, especially those from Portugal, being
perhaps the roughest. Others appear quite smooth to the touch, and this is
the case with many English specimens. The skin of the under parts is more
granular and devoid of specific glands. The general colour of the upper
parts is olive grey to dark brown, more or less mottled; the under parts
are whitish, often with a brown, yellow or reddish tinge.
The coloration of this species varies considerably and is moreover very
changeable. These changes depend chiefly upon the surroundings and the
locality, in which certain styles of coloration seem to be the fashion, not
necessarily to the absolute exclusion of others. Some specimens are of a
rich brown colour, with or without dark brown spots and patches, and these
are sometimes confluent, forming irregular, longitudinal bands. The
ground-colour of other individuals is olive grey, with or without darker
patches, and these paler tones prevail in toads which live on
light-coloured soil, for instance on chalk. I recently found one between
two dark-coloured slates, and this creature was so black that it gave the
impression of having soiled itself with coal-dust. One and the same
specimen will appear paler or darker according to its mood and the leading
tones of its immediate surroundings, but it cannot change its dominant
ground-colour. A third colour-variety occurs more frequently in the
mountainous districts of Southern Europe. I have obtained the most handsome
specimens in the Serra Gerez, in North Portugal. Their ground-colour is
pale brownish-yellow, with many large and small, rich brown patches, or if
the latter colour predominates, these patches and spots are separated from
each other by creamy seams, with the occasional effect of dark brown,
yellow-ringed eyes. Eastern Asiatic specimens often have a fine yellow
vertebral line and the under parts are inclined to be marked with dark
spots.
The iris is red or coppery, mottled with black. The male {171}has no vocal
sacs, and, besides being smaller than the female, is distinguished by
slight nuptial excrescences in the shape of little horny brushes on the
inside of the inner palmar tubercle and the three inner fingers. The full
size of this toad varies extremely. Taking the standard of everyday
experience in England and Central Europe, one would call any female beyond
3½ inches in length, and any male of more than 2½ inches, unusually large.
But occasionally they grow to a much larger size, especially in the
mountains of Southern Europe, provided there is a rich vegetation of
meadows and deciduous trees so as to insure a variety of plentiful food.
Although Fatio[79] mentions a toad 153 mm. = 6 inches long, and Boulenger
succeeded in getting a toad from Paris which measured 132 mm., _i.e._
almost 5¼ inches, one of my specimens from the Serra Gerez seems to hold
the record with a total length from snout to vent of 135 mm. or more than
5¼ inches. Jersey is also famous for its large toads, possibly on account
of the many large greenhouses. These large specimens do not constitute a
special race. The monsters among them are without exception females, often
but not always sterile, as I have often found large masses of eggs in them.
Food is the chief cause. At least I have observed that the more voracious
of some Spanish and Portuguese specimens, which were already 3½ inches
long, and therefore entitled to respect, continued to grow rather rapidly,
adding about half an inch within a year. Again, if the growth of a
promising toad is arrested for a season–not necessarily by starvation, but
by uncongenial surroundings, sameness, and unvaried nature of food–they
consolidate so to say, or settle down, and no amount of future good feeding
will turn them into exceptionally big specimens. There are no data to tell
how old such monsters really are. At least ten years are required by the
Southerners to reach four inches. The usual length of life attained by a
toad is likewise unknown. Boulenger kept one in a box provided with a sod,
a pan of water and plenty of varied food, but twelve years of close
captivity did not make any appreciable difference in its appearance.
{172}[Illustration: FIG. 35.–_Bufo vulgaris._ Portuguese specimen. × ⅔.]
A number of large Spanish and Portuguese specimens in my greenhouse were at
first very shy, and tried every possible means of escape or sullen hiding,
but gradually they condescended to take food when lifted on to the
slate-covered stage upon which their food was spread. After a few weeks
they had learned this so thoroughly that, towards the usual hour of
feeding, they climbed most laboriously on to the slates, lying in wait
between the flower-pots, and coming forward when we entered the house. The
rest of the day and night they spent on the ground, under stones or plants,
each in its individual lair. The biggest of all, and several others, became
so tame that they took food whilst sitting on the hand, and then they
looked up for more. The food must be alive and show movement. Mealworms,
snails, beetles and other small creatures are first carefully inspected
with bent-down head, and are sometimes followed for a few inches; then
comes an audible snap, a flash of the rosy tongue and the prey has
disappeared. Large earthworms are nipped up with the jaws and laboriously
poked in with the hands, the fingers being so placed as to clean the worm
of adherent soil and other impurities. Very large worms are shaken,
twisted, pressed against the ground and gulped down with convulsive
movements, but not unfrequently the tip-end remains for some minutes
sticking out of the tightly shut mouth. Several are taken at one sitting,
until the toad is gorged. One of the biggest took full-grown mice, which
{173}were not "fascinated by the fiery eyes" but were stalked into a corner
and then pounced upon immediately when they moved. The shells of snails can
for half a day be felt through the body; they then dissolve or are
disgorged. The dung, which is passed in large, long masses, is often full
of fine earthy matter, the contents of the earthworm's intestines, and
sometimes it contains the chitinous remains of certain beetles which are
supposed to be excessively rare. I know of no instance of slugs being
eaten.
The regular hunting-time begins with the evening and is continued
throughout bright nights, the toads crawling and hopping about. They are
expert climbers of rocks, and succeed in reaching apparently inaccessible
places by shoving themselves up between vertical walls, and taking
advantage of any roughnesses for foothold. Every few weeks they shed their
skins. Without any preliminary symptoms or loss of appetite or liveliness,
the body makes a few twisting motions, the back is now and then curved, and
the skin splits down the middle line. Owing to the more forcible
contortions of the body it slides down to the right and left of the back,
whereupon the toad gets hold of the peeling-off skin with fingers and toes,
scraping the head and sides, and conveys the thin, transparent, slightly
tinged skin into the mouth, slips out of it backwards and swallows it. The
new surface is then quite wet and shiny, but it soon dries and hardens.
Many toads, for instance the Common Toad and the Pantherine Toad, assume a
peculiar attitude when surprised. Instead of blowing themselves up by
filling their lungs with air, they raise themselves upon their four limbs
as high as possible, but turning the back towards the enemy in a slanting
position, either to the right or to the left side, apparently in order to
present as much surface as possible, in other words to look their biggest.
Some of my specimens hibernated regularly for a few months, burying
themselves completely in loose, dry soil, under leaves, or,–a favourite
place,–in a heap of cocoa-nut fibre. Others, and this applies also to
English specimens transferred from the garden into the greenhouse, are
lively all the year round, but even they withdraw for an occasional sleep
of a few weeks at any time of the year.
The whole family of large toads came to a sad end after four years, when
they were put into new temporary quarters, a {174}slate-bottomed terrarium.
Being kept during my absence in wringing wet moss, which became fouled by
their own excretions, they contracted a mysterious disease from which they
never recovered. They are rather averse to wet surroundings, and except
during the short pairing season they live in cool, shady places, preferably
with just a little dampness. Occasionally they take a soaking bath. One
specimen, living in the garden, repaired during the hot and dry summer
nights to a standpipe in the garden, enjoying the occasional drips of
water.
Considering the amount of snails and other noxious creatures destroyed by
them during their regular nocturnal hunts, toads are eminently useful
creatures. Nevertheless, they suffer much through the stupid superstition
of people who ought to know better. It is difficult to find a gentle,
absolutely harmless and useful creature that is more maligned than the
European toad. It brings ill-luck to the house, the "slimy toad" spits
venom, sucks the cows' udders and after that destroys their power of giving
milk; it poisons the milk in the cellar, and a certain builder's horse,
which was grazing in the grounds of the Cambridge Museums, and died there
from a large concrement obstructing its bowels, was solemnly declared to
have swallowed one of my toads. Silly superstitions, owing to faulty, or
rather entire want of, observation! The toad is not slimy, but dry; it is
often found in buildings, where it keeps down the woodlice; it cannot suck,
nor does it drink at all; it does not spit venom, but becomes covered with
milky white and very strong poison when in acute agony, for instance when
trodden upon; and unless the big skin-glands be forcibly squeezed, there
will be no squirting. Therefore, leave it alone, or put down food on its
evening beat, and it will soon come to know and to recognise its friends.
The Common Toad can exist without food for a long time, provided the
locality is cool and damp, but it wastes away almost to skin and bones. In
order to disprove the persistently cropping up fable and sensational
newspaper-accounts of toads having been discovered immured in buildings,
where they were supposed to have lived for many years, Frank Buckland put a
dozen specimens into separate holes bored in a block of porous limestone,
covered them up tightly with a glass plate and buried the block a yard deep
in the soil. A second dozen were treated similarly, but were put into a
block of dense sandstone. After a {175}year and two weeks all the toads
enclosed in the latter block were of course found dead and decomposed, but
most of those in the porous block were still alive, with their eyes open,
and did not succumb to starvation until eighteen months of confinement.
These poor creatures could of course not move about, and were practically
undergoing enforced continuous hibernation. Otherwise they would soon have
wasted away and have died within six months. Those which tumble into deep
and dry wells remain rather small, but generally manage to keep alive for
years on the spiders, woodlice, earwigs and other insects which likewise
tumble in.
Toads hibernate far from the water in dry holes or clefts, retiring in the
middle of October in Central Europe, and they do not reappear before March.
Soon after, and this depends naturally upon the season, they congregate in
ponds or pools, and the males, which far outnumber the females, for whom
they fight, make a peculiar little noise, something like the whining bleat
of a lamb, uttering this sound day and night. The male having, after much
wrestling with competitors, secured a female, which is often several times
bigger than himself, clasps her tightly, by pressing his fists into the
armpits, and the pair swim or crawl about in this position sometimes for a
week before the spawning takes place. The number of eggs laid at one
sitting is enormous, varying from 2000 to 7000. They are very small, only
1.5-2.0 mm. in diameter, and are expelled in two double rows or strings,
one coming out of each oviduct. These strings consist of a soft gelatinous
mass, in which the double rows of entirely black eggs are imbedded, and
they measure in the swollen condition about 6 mm. or ¼ inch in diameter,
and from 10 to 15 feet in length. The strings are wound round and between
water-plants by the parents, which move about during the laying and
fertilising process. According to the coldness or warmth of the season the
larvae are hatched in about a fortnight, and for the next few days they
hang on to the dissolving gelatinous mass of the egg-strings. They then
leave the slime and fasten themselves by means of their suckers to the
under side of grasses and water-plants or sticks, with their tails hanging
downwards, still in a rudimentary condition, but henceforth progressing
rapidly.
Fischer-Sigwart[80] found the time of development as follows:–The {176}eggs
were laid on the 6th of March; the larvae left the jelly on the 16th, being
4 mm. long. On the 2nd of April they measured 13 mm.; on the 25th, 20 mm.
On the 7th of May the hind-limbs appeared. On the 18th of May the tadpoles
had reached their greatest length, namely 24 mm., and this is a rather
small size for so large a species. The fore-limbs broke through on the
28th, and the metamorphosis was completed eighty-five days after the eggs
were laid, the creatures leaving the water on the 30th of May. The tadpoles
showed a preference for rotten pieces of _Agaricus_, which were floating in
the water. The little baby-toads are surprisingly small, scarcely 15 mm.
long, and live in the grass, under stones, in cracks of the ground, and hop
about in much better style than their heavier and more clumsy-looking
parents. Where many broods have been hatched they can be met with in
myriads, the ground literally swarming with them, and as they are naturally
stirred up by a sudden warm rain, perhaps after a drought, people will
occasionally state it as an observed and well-ascertained fact that "it has
rained toads."
What becomes of all these hopeful little creatures? Although it takes them
fully five years to reach maturity, one would expect that the whole country
would be swarming with toads; but since this is not the case, there being
not more toads now than there were before, it follows that their enormous
fecundity is only just sufficient to keep the race going. Adult toads seem
to have scarcely any enemies except the Grass Snake, which takes them in
default of anything better. But how about the reduction where there are no
snakes? We know nothing about epidemics which might carry them off, but
elderly toads are liable to a horrible disease produced by various kinds of
flies, notably by _Lucilia bufonivora_ and _Calliphora silvatica_, the
maggots of which somehow or other eat their way from the nostrils into the
brain and into the eyes. Those which reach the brain at first produce
effects similar to those of _Coenurus cerebralis_, the hydatid or
bladder-worm of sheep. The toad inclines its head towards one side, and
cannot crawl straight, but walks in a circle. By eating away the brain they
gradually destroy the host's life. But if none enter the brain, and a few
only find their way into the eye, they only impair or destroy its sight.
Such toads show signs of pain, poking at or stroking the affected eye,
which becomes {177}inflamed, and ultimately remains enlarged, with the iris
partially or entirely destroyed by the maggot, which does not develop
further, but dies in the eye-chamber, this being really an unsuitable place
for it. The eyesight is of course affected, and is mostly, but not in all
cases, lost. Such half-blind individuals–the disease affecting sometimes
one eye only–recover their health, and except for a little awkwardness,
behave like normal specimens. This applies to _Bufo vulgaris_ as well as to
_B. calamita_. Australian Anura are cursed with a fly of their own, called
_Batrachomyia_.[81]
_B. vulgaris_ inhabits almost the whole of the Palaearctic region;–the
whole of Europe, with the exception of Ireland, the Balearic Islands,
Sardinia and Corsica. Northwards it extends to Trondhjem, and thence along
a line drawn across Russia and Siberia to the Amoor. Its southern limit in
Asia is indicated by a line drawn from the Caucasus through the Himalayas
into China. In Asia Minor and in Persia it is absent. South of the
Mediterranean it occurs only in Morocco and Algeria.
_B. melanostictus_ is the common toad of the whole Indian region and of the
Malay Archipelago. The epidermis of the fingers and toes is thicker and
more cornified than usual, and is stained black brown, hence its specific
name. The male has a subgular vocal sac. In other respects the Indian
species much resembles the more spinous or rough-skinned and brown
varieties of the European species. According to S. S. Flower this toad is
very common in the Straits Settlements, hiding by day under stones or logs,
or in holes, coming out shortly before sunset, and remaining abroad till
dawn; it may be met with on the roads and in the grass, hopping or crawling
about in search of ants, bees, and similar food. It utters a rather feeble,
plaintive cry when handled for the first time. It can change its colour
from light yellowish to dark brown. The spawn, which resembles that of _B.
vulgaris_, may be seen in March and April in ponds, in long strings twined
about the water-weeds. The tadpoles are very like those of the common
English toad in form, size, colour, and structure of mouth. The largest
adult found in Penang measured 115 mm. (about 4 inches) from snout to vent.
{178}_B. lentiginosus_ s. _americanus_ is the common toad of North America,
from Mexico to the Great Bear Lake. It is worth noting that this species
resembles in its coloration the Eastern races of _B. vulgaris_, in so far
as they generally have a light vertebral line, and frequently dark spots on
the under surface. The upper parts are brown and olive, with darker spots,
two of which form a chevron behind the eyes. But the tympanum is large, and
the male has a subgular vocal sac; the inner metatarsal tubercle is very
large, and is used as a kind of digging spur. During the pairing time they
take to the pools in great numbers, uttering their music, which consists of
a prolonged trill, continued by different individuals, both day and night.
Holbrook knew an individual which was kept for a long time, and became
perfectly tame. During the summer months it retired to a corner of the room
into a habitation which it had prepared for itself in a small quantity of
earth placed there for its convenience. Towards the evening it wandered
about in search of food. Some water having been squeezed from a sponge upon
its head one hot day in July, it returned the next day to the spot, and
seemed well pleased with the repetition, nor did it fail during the extreme
heat of the summer to repair to it frequently in search of its shower-bath.
Several varieties of this widely distributed species, whose average length
is 2½ inches, have been described. The prettiest was called _B. quercinus_
by Holbrook–according to whom it is mostly found in sandy places covered
with a small species of oak–which springs up abundantly where pine-forests
have been destroyed. It is called the "oak-frog," as it spends most of its
time in concealment under fallen oak-leaves, or partially buried in the
sand.
_B. marinus_ s. _agua_ is the giant among toads, and is one of the
commonest species of the Neotropical region, ranging from the Antilles and
Mexico to Argentina. It frequently reaches a length of 6 inches, with a
width of 4 inches when squatting down in its favourite attitude. The upper
parts are rough, owing to the prominent warty glands, of which the parotoid
complex is enormous. The general colour above is dark brown, with sooty
dark patches; below whitish, often with blackish patches. This creature
appears at dusk, often in large numbers, especially during the rainy
season, hopping about, not crawling, with surprising {179}activity. The
voice of the male, strengthened by a subgular sac, is said to be a kind of
loud snoring bark. The pairing time begins, according to Hensel,[82] with
the winter rainy season, especially June, and lasts several months, until
October, but it is interrupted by the cold, which in the hills of
South-Eastern Brazil covers the ponds with ice. Then the tremulous bass
voice of the males is heard no longer; they have all withdrawn beneath
stones and trees in the neighbourhood of the water. The eggs are laid in
strings. The larvae are at first quite black and very small, and the young
baby-toads are only 1 cm. in length. They differ considerably from the
adult until they are more than 1 inch long; the upper parts are yellowish
brown, with darker ocellated patches, each with a light seam, most
conspicuous along the sides of the head and back. The under parts are grey,
finely stippled with yellow.
Budgett[83] remarks that _B. marinus_ feeds on all kinds of insects. "One
half-grown specimen sitting by a man's foot picked off fifty-two mosquitoes
in the space of one minute, picking them up with the tongue as they
settled. The call of this very common toad consists of three bell-like
notes; the middle one being the highest. The enormous parotoid glands are
discharged like squirts when the creature is roughly handled. When wet
weather comes on it hops out from its hiding-place to sit in a puddle, with
its head out."
In many species of _Bufo_ the crown of the head forms more or less
prominent ridges, especially strong in the region between the eyes; for
instance, in _B. melanostictus_ and _B. lentiginosus_. The skin overlying
these ridges is liable to be involved in the cranial ossification, and this
reaches its greatest extent in the two Cuban species _B. empusus_ and _B.
peltocephalus_. It is a curious coincidence, to say the least, that such
dermal ossifications should be best developed in Neotropical species, in
those very countries which amongst the Cystignathidae have produced the
abnormal genera _Triprion_, _Calyptocephalus_, and _Pternohyla_. The most
peculiar and odd-looking species is _Bufo ceratophrys_, a native of
Ecuador, which has the upper eyelid produced into a horn-like appendage,
the two sharply-pointed cones standing out transversely, reminding us of
several species of the Cystignathoid genus _Ceratophrys_; there is also a
series of four small pointed {180}appendages on each side of the body.
Protective concealment is possibly the reason of these queer outgrowths.
_B. viridis_ s. _variabilis_, the Green or Variable Toad, reaches a length
of about 3 inches, and is the prettiest toad of Europe. The skin is
distinctly smooth, the numerous porous, large and small warts being
flattened. Parotoid glands are well developed, and a similar pair of glands
sometimes occurs on the inner side of the calf, especially in Central
Asiatic and in Algerian specimens. The coloration is very variable and
changeable. The ground-colour of the upper parts is creamy, with large and
small, partly confluent and irregularly shaped spots and patches of green,
here and there interspersed with vermilion-red specks, especially along the
sides of the back. The under parts are whitish, sometimes spotted with
black. The iris is brass-coloured, greenish-yellow, with fine dark dots.
The male does not differ from the female in size, but has an internal
subgular vocal sac, a conspicuous callosity on the inner side of the first
finger, and nuptial brushes on the first three fingers and on the inner
palmar tubercle.
The changing of colour affects mainly the intensity of the green; the same
individual which now looks almost uniformly dull, almost grey, with dusky
olive patches, will, if put into grass and sprinkled with water, within a
few minutes appear in a tastefully combined garb of grass-green on a creamy
ground. Some Southern and Eastern specimens have a creamy stripe along the
vertebral line, thereby closely resembling _B. calamita_, from which,
however, they can always be distinguished by the little pads below the
joints of the toes; these pads being single in B. viridis, and double in
_B. calamita_ and in _B. vulgaris_.
The Green Toad spends most of the day in holes, although it is not averse
to daylight, and it roams about chiefly in the evening. It can jump well,
much better and oftener than the Brown Toad. The food consists strictly of
insects of all kinds, and most individuals prefer slow starvation to eating
an earthworm. Although continuing to live four or five years in captivity,
they do not readily become tame; they are indeed no longer wild, and when
handled they no longer emit their peculiar insipid smell, but on being
approached they still crouch deeply into the grass, or withdraw into their
holes, just as they did when recently caught. The voice is heard during the
pairing season, and sounds like the slow creaking of a door, or a
combination of a spinning top and {181}rattle. In Germany, during the
months of April and May, they take to the ponds, or, improvident like the
common frog, to a roadside ditch. The male sits upon the female and grasps
her below the arms, his hands on her breast, and in this position they
remain for days. The eggs are laid in two strings, twisted around
water-plants, and are very numerous. Héron-Royer has calculated them at
10,000 or more in one set. The embryos are hatched, like those of the
Common Toad, before the appearance of the external gills and of the tail.
In this imperfect condition they remain in the jelly of the egg-strings for
a few days, while their external gills sprout out like unbranched little
stumps, only to disappear again. In about eight weeks the tadpoles, which
reach a length little more than 1½ inch or 40 mm., have metamorphosed and
leave the water as baby-toads scarcely half an inch in length.
This species has a very wide range, namely, the whole of Middle Europe
excepting the British Isles, France and the Iberian Peninsula; the region
between the Elbe and Rhine being its western limit; southwards it extends
over all the Mediterranean islands and the north coast of Africa, eastwards
through the whole of Russia, Western and Central Asia, not entering India,
but spreading along the Himalayas into China. Stoliczka mentions its having
been found in the Himalayas at an altitude of 15,000 feet, the highest
record of any Amphibian, at least in such latitudes.
_B. calamita._–The Natterjack is practically the representative of the
Green Toad in Western Europe, but both species occur together in Denmark,
Southern Sweden, and nearly the whole of Germany. Its southern limit is
Gibraltar. In the British Isles it occurs in South-Western Ireland, in Co.
Kerry, and in England and Wales, being however local, and preferring sandy
localities, where it is found in considerable numbers. This predilection is
shown by its frequency on the sandy dunes of most of the islands off the
German and Dutch coast, where it may be seen running about in glaring
sunshine.
Besides in the coloration, it differs from _B. viridis_ in the following
points. The little subarticular pads of the toe-joints are paired, not
single, and the hind-limbs are decidedly shorter, so much so that this
species cannot hop. But it runs well, like a mouse, generally in jerks,
stopping every few seconds, and owing {182}to this habit it is called the
"running toad" by the field-labourers of Cambridgeshire. The skin is
smooth, but less so than in _B. viridis_, owing to the slightly more
prominent warts; the parotoids are small; a similar pair of glands lies on
the upper surface of the fore-arm and another on the calf. The tympanum is
rather indistinct. The ground-colour of the upper parts is light brownish
yellow, with a green tinge and scattered green spots; most specimens have a
narrow yellow stripe along the vertebral line and over the head. The under
parts are white, more or less speckled with black. The iris is greenish
yellow and speckled. The male, which is of the same size as the
female,–very large specimens reaching 3 inches in length,–has a large
subgular vocal sac, and develops nuptial brushes on the first three
fingers, but the first lacks the thickened pad of _B. viridis_.
The yellow vertebral line is sometimes absent in specimens from the south
of France and the Iberian Peninsula; and since these southerners are as a
rule more handsomely marked, the green being more pronounced and arranged
in larger patches, interspersed with red spots, they much resemble _B.
viridis_. Boulenger, who has paid especial attention to this vertebral
streak, which is a not uncommon design in various species of different
families, has made the interesting observation that the streak has never
been found in Danish and German specimens of _B. viridis_, where _B.
calamita_ occurs also, while it is not uncommon in _B. viridis_ of Italy,
South-Eastern Europe, Asia, and North Africa, where _B. calamita_ is not
found. Lastly, he remarks that in Eastern Asia, where neither _B. viridis_
nor _B. calamita_ with such a line occurs, the same character is assumed by
some specimens of _B. vulgaris_. The only conclusion we can draw from these
facts is, that for some unknown reason the streak is a desirable, but not
necessary, possession, but that it is not kept by two species in the same
country, _B. viridis_ dropping it entirely where the typically streaked
species, _B. calamita_, also occurs. The breeding season does not begin in
England and Middle Europe until the end of April, in cold springs not
before May, but it lasts for several months. The males, congregating in
pools in great numbers, make a loud noise, each individual uttering a
rattling note which lasts a few seconds, the repetition distending its
bluish throat into the shape of a {183}globe as large as its head. As the
note is taken up by all the other males, a continuous chorus is
established, which on warm and still nights can be heard nearly a mile off.
Single croaks are uttered at any time of the day. The embrace, the male
digging its fists into the armpits of the female, often takes place on
land, near the edge of the water, to which they resort in the night for
spawning. The egg-strings are slung around water-plants, unless the water
is a mere puddle, and are much shorter than those of _B. viridis_,
measuring only 5 to 6 feet, and containing altogether 3000 to 4000 eggs.
The larvae, when hatched, are very small, imperfect, and blackish; the
external gills last a very short time. The young tadpoles live on mud,
subsisting on diatoms and low Algae; they are the smallest tadpoles of all
the European kinds, scarcely reaching more than one inch in length, and
they metamorphose quickly, the baby-toads leaving the water and running
about in less than six weeks, when they are only 10 mm., scarcely
three-eighths of an inch, in length. By the end of their second summer they
are still only three-quarters of an inch long, and they do not reach
maturity until the fourth or fifth year, with a size of 1½ to 2 inches;
still smaller young males become mature several years before they are full
grown.
Natterjacks stand captivity well and become very tame. When discovered,
they first do their best to run away, instead of hiding or squatting down,
and when caught they become covered with a slightly foamy lather, the
exudation of their glands, which has a peculiar smell, reminding some
people of gunpowder, others of india-rubber. They are not very particular
as to food, all sorts of insects and earthworms being taken. Natterjacks
are great climbers and diggers. Many of mine have established themselves in
the peat with which the walls of the greenhouse are covered, where they
have dug out, or enlarged, holes in which they pass the daytime, just
peeping out with their bright eyes; others sit high up, always in dry
places, and bask. In the evening they descend, hunting about on the ground,
and occasionally they go into the water, whereupon they become quite
flaccid and soft. When taken up and held between two fingers, being
slightly pressed under the armpits, both sexes utter little jerky notes,
as–by the way–most toads and frogs do under similar conditions.
In Cambridgeshire they frequent certain clay-pits surrounded {184}by high
and steep walls of sand, the breeding places of large colonies of
sand-martins. During the months of May and June they are found in the
shallow water, running about on the mud, sometimes swimming, in which they
are not very proficient, and rarely diving. But they spend most of the time
on land. Early in October they climb up and enter the holes of the
sand-martins, or they dig large, deep burrows for hibernation, and the old
males are the first to disappear.
_B. mauritanica_ s. _pantherina_.–The "Pantherine Toad" is one of the few
African species, and is one of the prettiest of all toads. The skin is
almost smooth, although provided with porous glands. The parotoids are
large, but flat; large glandular complexes on the legs or arms are absent.
The tympanum is very distinct. The upper parts are adorned with a delicate
pattern of dark-edged, rich brown or olive patches upon a light,
buff-coloured ground; the under parts are uniform white; the male has a
subgular vocal sac. The total length is 3 to 4 inches. This beautiful
species is one of the gentlest, and it becomes tame enough to lap up food
whilst sitting on one's hand. It lives entirely upon insects, prefers shade
and dusky light, and utters a sound like "kooh-rr." It is a native of
North-Western Africa, Algiers, and Morocco. In the rest of Africa, from
Egypt to the Cape, Senegambia to Abyssinia, it is represented by _B.
regularis_. This species has often little spiny tubercles upon the warts,
and occasionally a light vertebral line; the colour of the upper parts
either closely resembles that of the previous species, or it is uniform
light brown, while the under parts are whitish, or variegated with brownish
patches. West African specimens are the smallest, only 2 inches long; those
of the Cape are the largest, reaching 5 to 6 inches.
The next two genera approach the Engystomatinae, and thereby lead from the
arciferous towards the firmisternal type. The epicoracoid cartilages are
narrow, and they scarcely overlap, so that by a further step in this
direction they could easily fuse into the firmisternal condition. Another
bond between these two genera and the Engystomatinae is their habits, they
being ant-eaters of an extremely stout appearance, with exclusively short
limbs and very small heads.
_Myobatrachus gouldi_, living in Australia, has a smooth skin, brown above,
lighter beneath, and is about 2 inches long.
{185}_Rhinophrynus dorsalis_ of Mexico is remarkable for its tongue, which
is elongated, subtriangular and free in front, so that it can be protruded
directly–not by reversion as in other toads–and can be used for licking up
the termites which seem to be its principal food. The body of this ugly
creature is almost egg-shaped, and the head is merged into this mass, only
the narrow truncated snout protruding. The limbs are very short and stout.
The toes are more than half webbed, and there is a large oval, shovel-like
metatarsal tubercle, covered with horn and used for digging. The general
colour is brown, with a yellow stripe along the spine and with irregular
spots and patches on the flanks and limbs. Total length 2 to 2½ inches.
[Illustration: FIG. 36.–Map showing distribution of Hylidae. The vertically
shaded countries are inhabited by _Hyla_ and by other genera of Hylidae;
the horizontally shaded countries only by _Hyla_.]
FAM. 4. HYLIDAE (Tree-frogs).–The upper jaw–in _Amphignathodon_ the lower
jaw also–and the vomers carry teeth; _Triprion_ and _Diaglena_ alone have
teeth on the parasphenoid also, and the latter genus is further
distinguished by possessing palatine teeth. The vertebrae are procoelous
and have no ribs; the sacral diapophyses are dilated. The omo- and
meta-sternum are cartilaginous, the latter forming a plate with scarcely
any basal or style-shaped constriction. The terminal phalanges are
invariably claw-shaped and swollen at the base, and carry a flattened,
roundish, adhesive cushion. The tympanic disc is variable in appearance,
being either free, or more or less hidden by the skin. The tongue is also
variable in its shape and in the extent to which it can be protruded.
{186}Most, if not all, Hylidae are climbers, and many lead an arboreal
life, but it does not follow that all the "Tree-frogs" are green.
Their distribution is very remarkable. To say that this family is
cosmopolitan with the exception of the African region, is literally true,
but very misleading. There are in all about 150 species, and of these 100
are Notogaean; one-half of the whole number, or 75, being Neotropical; 23
are Central American, 7 Antillean, and about 18 are found in North America.
One species, _Hyla arborea_, extends over nearly the whole Palaearctic
sub-region, and two closely allied forms occur in Northern India and
Southern China. Consequently, with this exception of three closely allied
species, the Hylidae are either American or Australian. We conclude that
their original home was Notogaea, and that they have spread northwards
through Central and into North America. The enormous moist and steamy
forests of South America naturally suggest themselves as a paradise for
tree-frogs, and it is in this country, especially in the Andesian and the
adjoining Central American sub-regions, that the greatest diversity of
generic and specific forms has been produced. It is all the more remarkable
that similar forest-regions, like those of Borneo and other Malay islands,
are absolutely devoid of Hylidae (while there are about a dozen species in
Papuasia), whose place has however been taken for all practical purposes by
correspondingly modified Ranidae, notably the genus _Rhacophorus_. Lastly,
the fact that tropical evergreen forests of Africa and Madagascar possess
no Hylidae, but are inhabited by several kinds of tree-climbing
_Rhacophorus_, points with certainty to the conclusion that the origin of
this large and flourishing family of Hylidae was not in Arctogaea.
The versatility and the wide distribution of the Hylidae has naturally
produced cases of convergent analogy, and the various species of one
"genus" may be in reality a heterogeneous assembly. Such an instance is
probably the genus _Hylella_, of which four species live in the Andesian
and Central American provinces, while the two others occur in New Guinea
and Australia.
The two North American genera _Chorophilus_ and _Acris_, and the Brazilian
_Thoropa_, connect the Hylidae with the Cystignathidae, in so far as their
finger-discs are very small, or even {187}absent, and their sacral
diapophyses are only slightly dilated. On the other hand, it has to be
emphasised that the possession of adhesive discs on the fingers and toes
does not necessarily constitute a member of the Hylidae. That requires _the
further combination of an arciferous sternum, with dilated sacral
diapophyses and teeth in the upper jaw_. Finger-discs are easily developed,
and still more easily lost. Those of the typical Hylidae are constructed as
follows. The terminal phalanx is elongated, claw-shaped, swollen at its
base. Between it and the penultimate phalanx lies an interphalangeal
cartilaginous disc which projects ventrally below the end-phalanx, thus
assisting the formation of the ventral pad, and the turning upwards of the
whole disc-like phalanx like the claw of a cat. This peculiar motion can be
well observed in Tree-frogs which are at rest upon a horizontal leaf, or,
better still, upon a rough stone, when the creatures take good care to
adjust their discs into a safe and easy position. The pad or disc itself is
furnished with unstriped, smooth muscular fibres, the contraction of which
produces one or more longitudinal furrows on the under side. When the disc
is in action or adhering, being flattened to a smooth surface, the
end-phalanx sinks into the cushion; when not in action, the cushion swells
and the phalanx appears as a slight dorsal ridge. The disc is rich in
lymph-spaces, and its surface contains mucilaginous glands.
Various suggestions have been made to explain the function of these discs.
Suction, adhesion, and glueing-on have been resorted to. Suction, through
production of a vacuum, is quite imaginary and does not exist. The question
has been thoroughly studied by Schuberg.[84] Adhesion is due to the
molecular attraction of two closely appressed bodies. The less air remains
between them the stronger it is. Consequently it can be increased by the
interference of a thin layer of fluid, which as everyday observation shows,
possesses both adhesion and cohesion. The more sticky the fluid, the more
effective it is, as shown experimentally by Schuberg, who moistened the
under surface of a glass plate, and pressed it against a little disc of
glass from which was suspended a weight. A disc of 16 square millimetres,
approximately equal to the aggregate surface of the 18 discs of a European
tree-frog of 4 grammes in weight, carried with water-adhesion {188}no less
than 14 grammes, with glycerine-solution 20 grammes,–more than sufficient
to suspend the frog. The sticky secretion of its glands greatly enhances
the adhesive power. Tree-frogs, when hopping on to a vertical plane of
clean glass, slide down a little, probably until the secretion stiffens, or
dries into greater consistency. After a few days I find the glass-walls of
their recently cleaned cage quite dirty, covered everywhere with their
finger-marks. On the other hand, wet leaves or moist glass-walls afford no
hold. The adhesion of these frogs is assisted in most cases by their soft
and moist bellies, just as a dead frog will stick to a pane of glass.
All Hylidae have a voice, often very loud, and enhanced by vocal sacs,
which are either internal, swelling out the throat, or external, paired or
unpaired.
The various Hylidae resort to all kinds of modes of rearing their broods.
Most of them lay many eggs, up to one thousand, in the water, not coherent
in strings but in clumps; others lay only a few, attach them to various
parts of the body, or, as in the genus _Nototrema_, the female receives
them in a dorsal pouch. These modifications will be described in connexion
with the different species.
SUB-FAM. 1. AMPHIGNATHODONTINAE.–_Both upper and lower jaw with teeth._
_Amphignathodon_, of which only one species is known, _A. guentheri_ of
Ecuador, agrees with _Nototrema_ in all important characters except that it
possesses teeth in the lower jaw in addition to those in the upper. There
are further differences, but they are of degree only. The sacral
diapophyses are more strongly dilated and the omosternum is absent. The
tympanum is distinct. The pupil is horizontal; the roundish tongue is
slightly free behind. The terminal phalanges are claw-shaped and carry
large discs. The female has a dorsal pouch opening backwards. The skin of
the head is involved in the ossification of the cranial bones. The skin of
the back is smooth, slightly tubercular, non-granular below. The middle of
the upper eyelid carries a small, pointed, cutaneous appendage, and even
this little character occurs also in some species of _Nototrema_, _e.g._ in
_N. longipes_ and in _N. cornutum_. The heel carries a triangular little
flap. The upper parts are olive in spirit-specimens, probably green in
life; the borders of the dorsal pouch {189}are black. The sides of the body
are adorned with a black, white-edged streak, the limbs are whitish, with
black cross-bars. The total length of the female type-specimen is 3 inches.
SUB-FAM. 2. HYLINAE.–_Lower jaw toothless._
The Hylinae are divided by Boulenger into 13 genera, which can be
recognised by the following key, without reference to their natural
affinities:–
_A._ The contracted pupil forms a horizontal slit.
_a._ Tips of the fingers and toes with large discs,
α. With vomerine teeth.
Female without a dorsal pouch .......... _Hyla_, p. 189.
Female with a dorsal pouch .......... _Nototrema_, p. 202.
β. Without vomerine teeth .......... _Hylella_, p. 203.
γ. With parasphenoid teeth and peculiar helmet-shaped head.
Yucatan .......... _Triprion_, p. 207.
Ecuador and Mexico .......... _Diaglena_, p. 207.
_b._ Tips with very small discs. Tongue free behind.
Tympanum distinct. North America and Peru .......... _Chorophilus_,
p. 208.
Tympanum indistinct. North America .......... _Acris gryllus_,
p. 207.
_c._ Tips simply swollen, not dilated into discs. Brazil ..........
_Thoropa miliaris_, p. 209.
_B._ The contracted pupil forms a vertical slit. Tropical America.
_a._ Tips with large discs.
α. Tongue extensively free behind.
Inner finger and toe opposable .......... _Phyllomedusa_, p. 203.
Inner finger and toe not opposable .......... _Agalychnis_, p. 206.
β. Tongue scarcely free behind. Ecuador .......... _Nyctimantis
rugiceps_, p. 206.
_b._ Tips without discs. Without parasphenoid teeth, but head peculiar
in shape. Mexico .......... _Pternohyla fodiens_, p. 207.
_C._ Pupil rhomboid. Without parasphenoid teeth. Large discs. Head
helmet-shaped. Brazil .......... _Corythomantis greeningi_, p. 207.
_Hyla._–The pupil is horizontal. The tympanum is distinct or hidden. The
tongue is entire or slightly nicked in its hinder margin, which is more or
less free behind. The fingers and toes are provided with typical adhesive
discs.
This is the largest genus of all Amphibia, containing about 150 species,
and its distribution coincides with that of the whole family. Many of the
species are very closely allied to each {190}other, differing only in small
points, for instance in the extent of the webs to the fingers and toes, the
configuration of the vomerine teeth, the size and appearance of the
tympanic disc, and the relative length of the hind-limbs. In some of the
West Indian, and in one Brazilian species, _H. nigromaculata_, the upper
surface of the head is rough, owing to the cutis being involved in the
cranial ossification. Bony or perhaps only calcareous deposits in other
parts of the skin are rare, but are notably developed in _H. dasynotus_ of
Brazil, in which they extend from the head to the sacrum, rendering the
skin immovable.
Many are capable of changing colour to a great extent, and it is a popular
error to suppose that all tree-frogs are green, although this colour is
perhaps the most common in the arboreal kinds.
[Illustration: FIG. 37.–_Hyla arborea_, var. _meridionalis_. South European
Tree-frog, × 1.]
_H. arborea._–The tongue is rather round, slightly nicked behind, and can
be protruded but little. The tympanum is distinct, but small. The upper
parts are grass-green, quite smooth and shiny owing to the skin being
covered with a film of moisture; the under parts are yellowish-white and
granular, flesh-coloured or rosy on the thighs. Total length of large
females 2 inches. This, the Tree-frog of Europe, has an enormous range,
namely, from Morocco, France, and the south of Sweden, across the whole of
Europe and Asia Minor to Japan and Southern China.
{191}Several varieties have been described: the _typical_ or _European
form_ is ornamented with a narrow black stripe, which, beginning at the
nose, extends backwards along the side of the body to the groin, where it
generally forms a hook turned upwards. This black colour forms the ventral
boundary of the green, and is itself narrowly seamed with white on its
upper border.
In the south of France, the Iberian Peninsula, Morocco, and the Canary
Islands the black lateral stripe is often absent; this is the var.
_meridionalis_. In Spain and Portugal both forms are found in the same
localities.
In the Asiatic, chiefly in the eastern specimens, the lateral stripes tend
to break up into irregular spots, vanishing altogether towards the groins;
this var. _savignyi_ s. _japonica_ occurs also on most of the Mediterranean
islands.
_H. arborea_ can change colour to a great extent, mostly in adaptation to
its immediate surroundings, but ill health and moulting may also influence
it. The change is slow. The usual colour is green, brightest on bright,
sunny hot days, dull when the sky is overcast, or when it is windy and
showery. Day and night have no influence upon the colour-changes. The hue
of the green agrees mostly with that of the foliage on which the frog
happens to take its rest, for instance a field of Indian corn, birch-trees,
or oak-trees. I once received a consignment from Saxony. When the box with
moss was unpacked, they were of the dullest greenish-grey; they were put
into a wired-off corner of the yard and were given the freshly cut branches
of a lime-tree to sit upon. On the following morning I at first looked for
most of the frogs in vain. The leaves had withered and all those frogs
which sat upon the dark brown branches had put on a light brown garb,
mottled with darker patches.
Another specimen, one of several which were at liberty in a greenhouse,
took to resting on the frame of the window-pane, in a corner where putty,
glass, and discoloured white paint met; in the morning it was always of a
mottled leaden colour, but during the nocturnal hunting it was green. In
the winter, the window-corner being of course cold, the frog remained
stationary for several months, but kept the leaden grey colour, until one
day in the early spring it was mottled with green, and soon after it joined
its green mates.
Liebe observed a half grown tree-frog which he kept in Gera {192}during the
winter in a glass with water-cress. While the temperature was near freezing
the frog sat in the water, very lethargic, breathing perhaps once every
quarter of an hour. Its colour was light green. When the water-cress was
cut and removed, the frog darkened and became at last quite a discoloured
grey. When the water-cress was put back, the creature reassumed the light
yellowish-green colour, remaining in its lethargic condition until it
became lively in the spring sunshine.
The European tree-frog spends most of its time in the summer, after the
pairing is over, in trees, often in the very crowns; but the neighbourhood
of even a small patch of Indian corn has still greater attractions. There
are all sorts of green insects to be caught, there are fair chances of
coming across the common Cabbage White, a butterfly which the tree-frog
loves, and last not least the large luscious leaves afford a firm foothold,
and the axillae between stalk and broad-based leaves are just the places
for the frog to slip into, where nobody can find it. During the day they
mostly sit still, on the keen look-out for passing insects, which, when
they settle within reach, are jumped at; otherwise they have first to be
stalked. The jump is quite fearless, regardless of the height above ground;
there is the leaf upon which the prey sits, and even if this leaf be
missed, there are others, and one of them is sure to be struck by some of
the discs of either fingers or toes. If the fall is broken by the toes, and
the new leaf or branch is very elastic and bends down, then there are some
frantic antics to be gone through until the frog has settled itself again.
Then the large blue-bottle, or the butterfly, is devoured at leisure, wings
and all being poked in with the assistance of the little hands. But the
real hunting-time is the night.
During a shower the frog shifts its position to the under side of the leaf,
or into a less slippery position, and during continuous wet it descends
into the grass, or it takes to the water. Its greatest enemy is the Grass
Snake, which prefers it to anything else, not minding the poisonous
secretion of the skin, which is sharp enough to produce sneezing or even
temporary blindness when incautiously brought into the human eye.
The male has an internal vocal sac, which, when inflated, bulges out the
whole throat into a globe, much larger than the head. The voice is a sharp
and rapidly-repeated note, something {193}like "epp-epp-epp," or "creck,
creck, creck," with more or less of an _a_ sound. It is uttered at any time
of the day, more frequently at dusk, and of course chiefly during the
pairing season. This tree-frog suffers from the reputation of being a good
weather-prophet, and it is for this reason often kept in confinement, the
orthodox abode being a muslin-covered glass jar, with a hole to put flies
through, water and plants at the bottom, and a little ladder to sit upon.
The prophesying is of the usual popular unreliable nature, although the
little creature, provided it is a male, often sounds its voice on the
approach of a shower, or when there is a thunderstorm in the air. During
continuous fine weather it sits on the top of the ladder, or is glued on
near the rim of the glass, while on wet and dull days it is less active,
and may keep nearer the ground or in the water. There is a German rhyme
which well expresses the prophet's reliability by its ambiguity:–
Wenn die Laubfrösche knarren,
Magst du auf Regen harren.
When the tree-frogs croak, you may wait for rain. Sometimes it does come
true.
Tree-frogs are not very intelligent, although they have a keen sense of
locality; but they are nice pets, being easily kept, and have a pretty
appearance. There is a record of one which lived for twenty-two years in
confinement.
The pairing begins soon after the frogs reappear from their hibernation in
the ground; in Germany in the month of May. The congregating males make a
great noise and take to the water before the females, which join them when
ready to spawn. The male grasps his mate near the shoulders, and the pair
swim about together, sometimes for days, until the eggs are expelled. These
are laid in small clumps of 800 to 1000, which soon swell up and remain at
the bottom of the pond. The larvae are hatched in ten days; two days later
the adhesive sucker below the throat appears, and after another two days a
pair of thread-like external gills are developed. The tadpoles, which reach
a length of 2 inches, owing to the long tail, which is nearly three times
as long as the body, metamorphose in about twelve weeks, and the baby
tree-frogs, scarcely half an inch in length, hide in the grass for the next
two years, until they are about half grown, not reaching maturity until the
fourth year.
{194}Since many pairs congregate in the same pool, and each produces up to
one thousand eggs, most of which are hatched, the neighbouring meadows
sometimes literally swarm with tiny tree-frogs. Nevertheless the adults are
comparatively rare and are very local.
_H. carolinensis_ s. _lateralis_ of the South-Eastern States of North
America greatly resembles _H. arborea_ in general appearance, size, and
habits. But the head is more pointed, and the vivid green of the upper
parts is separated from the yellowish white under surface by a conspicuous,
pure white line, giving the little creature a very smart and neat
appearance. According to Holbrook, it ascends trees, but most commonly lies
upon broad-leaved water-plants, like _Nymphaea_, and in fields of Indian
corn. Motionless during the daytime, they emerge in the morning and evening
from their hiding-places, and become very brisk and noisy, often repeating
their single note, which is not unlike that of a small bell. When one
begins, hundreds take it up from all parts of the corn-field.
Among other tree-frogs of the South-Eastern States may be mentioned _H.
squirella_, 1½ inch in length, which is very changeable in colour,
generally olive above with darker spots and bars on the limbs, and with a
white upper lip. It lives in trees, sheltering in the bark. _H. femoralis_
of the same size, without the white lip, lives high up in the trees of the
dense forests of Georgia and Carolina.
_H. versicolor_ is one of the most delicately coloured species of Eastern
North America, extending northwards into Canada. It is about 2 inches long.
Its colour passes within a short time from dark brown or olive grey to pale
delicate grey, almost white, occasionally retaining a few large darker
patches on the back, and delicate cross-bars on the limbs. A small portion
of the sides and the posterior part of the belly are bright yellow. The
skin is granular, owing to the presence of small warts which produce an
acrid secretion. It is said to be found in trees, or about old stone fences
overgrown with lichens, the colour of which it resembles to perfection. It
becomes very noisy towards the evening, in cloudy weather or before rain,
the voice consisting of a liquid note, terminating abruptly, like
"l-l-l-l-luk." My own captives fully bear out this statement of Holbrook's.
Settled motionless during the day upon a piece of bark in a shady
{195}corner, but occasionally uttering the quaint and rather faint note,
they become very lively in the evening, catching insects by long jumps, or
investigating the hollows of decaying mossy stumps. Their general colour is
then spotless, almost silvery grey. In the day-time they are sometimes
suffused with delicate green.
The propagation has been studied by Miss M. H. Hinckley.[85] They pair in
shallow pools, in Massachusetts, in May. On the 10th of that month eggs
were attached singly, and in groups, on the grasses resting upon the
surface of the water; first drab-coloured, they became lighter in a few
hours. Some larvae escaped from the gelatinous envelopes on the following
day, the others on the third day; they clung to the grasses by means of
their prominent suckers. The head and body were cream-coloured, with olive
dots, and averaged ¼ inch in length. Gills appeared on the fourth day, to
disappear again during the four following days, first those of the right,
then those of the left, side; the suckers became less conspicuous, and the
general colour turned into deep olive-green, with fine golden dots on the
upper and lower surfaces. The eyes were of a brilliant flame-colour. On the
eleventh day the suckers or "holders" had disappeared, and the hind-limbs
were indicated by small white buds. By June 5th, _i.e._ the twenty-seventh
day, the toes developed the terminal discs; the mottling of gold had given
way to a uniform olive or pea-green. Movements of the future arms beneath
the skin appeared on the 28th of June, at the age of seven weeks. The arms,
mostly the right one first, were thrust out on the 2nd of July; the fins of
the tail were absorbed rapidly, and towards the end of the seventh week the
nearly transformed creatures began to leave the water. The young frogs
changed colour rapidly, in adaptation to their surroundings, but the four
specimens which survived were never all found to be of the same colour
during the next three months. They first lived upon Aphides, later upon
flies, and they were alert nocturnally. About the beginning of October they
left the fronds of their fernery and nestled away in the damp earth, which
they left only when the temperature rose above 60° F.
_H. vasta_ of Hayti is the giant of the tree-frogs, reaching a length of 5
inches. In order to support its great weight the {196}adhesive discs of the
fingers and toes are of a surprising size, about as large as a threepenny
piece. The skin is covered with small warts, and forms a peculiar fold on
the hinder surface of the fore-arm and on the tarsus, and small flaps near
the vent. The colour is grey above, blackish on the head, with a brown band
between the eyes; the under parts are flesh-coloured, the throat with black
spots.
_H. maxima_, of the forests of British Guiana, is scarcely less gigantic,
and is distinguished by a projecting rudiment of the pollex, while the
adhesive discs are smaller than the tympanum. The skin forms folds on the
arms and tarsus, like those of _H. vasta_, in addition to a triangular flap
at the heel. The general colour is reddish-brown above, sometimes with a
dark vertebral line, the under parts are whitish and covered with large
granules; the throat of the male, which has an inner vocal sac, is brown.
_H. faber_ of Brazil is closely allied to the last species, but the skin of
its upper parts is quite smooth. There is a small tarsal fold, and one
extending from the upper eyelid to the shoulder. It is light brown above,
with darker marks which form a conspicuous vertebral line, transverse bars
on the hind-limbs, and a few irregular, scattered, vermicular or linear
marks on the head and body. The adult, when put into a strong light, will
rapidly turn pale; at night the longitudinal stripe on the back and the
bars on the hind-limbs become very distinct; the under parts are white, and
exhibit a beautiful orange tinge. This is the famous "_Ferreiro_" or
"smith." As will be seen from the following graphic account by Dr.
Goeldi[86] of Para, this species doubly deserves its name of _faber_, not
only in virtue of its voice, but also because of the marvellous
nest-building habits recently discovered.
"The _Ferreiro_ is common in the Province Rio de Janeiro, more frequently
still in the mountain regions of the Serra dos Orgãos than in the hot
lowland. Its voice is one of the most characteristic sounds to be heard in
tropical South America. Fancy the noise of a mallet, slowly and regularly
beaten upon a copper plate, and you will have a pretty good idea of the
concert, given generally by several individuals at the same time and with
slight variations in tone and intensity. When you approach the {197}spot
where the Tree-frog sits, the sound ceases. But keep quiet, and it will be
resumed after a few moments. You will discover the frog on a grass-stem, on
a leaf of a low branch, or in the mud. Seize it quickly, for it is a most
wonderful jumper, and it will utter a loud and shrill, most startling cry,
somewhat similar to that of a wounded cat."
The "Smith" makes very regular pools, in the shallow water of ponds, or
nurseries for the tadpoles surrounded by a circular wall of mud. Dr. Goeldi
has watched the building process during a moonlit night: "We soon saw a
mass of mud rising to the surface carried by a Tree-frog, of which no more
than the two hands emerged. Diving again, after a moment's time, the frog
brought up a second mass of mud, near the first. This was repeated many
times, the result being the gradual erection of a circular wall. From time
to time the builder's head and front part of body appeared suddenly with a
load of mud on some opposite point. But what astonished us in the highest
degree was the manner in which it used its hands for smoothing the inside
of the mud wall, as would a mason with his trowel. When the height of the
wall reached about 4 inches, the frog was obliged to get out of the water.
The parapet of the wall receives the same careful smoothing, but the
outside is neglected. The levelling of the bottom is obtained by the action
of the lower surface (belly and throat principally) together with that of
the hands."
The male takes no active share in the construction of the nest, but will
suddenly climb up the wall of his home, and then upon the back of his busy
mate. The building operation may take one or two nights, and is performed
in the most absolute silence; the croakers around are all males clamouring
for a mate.
The eggs are laid during one of the following nights, and are hatched some
four or five days later, the parents keeping hidden in the neighbourhood of
the nursery. Heavy rains may destroy the walls, and thus prematurely
release the tadpoles.
It is only owing to such keen observers and lovers of nature's fascinating
ways that the breeding habits of some Brazilian Hylidae have become known.
_H. nebulosa_ s. _luteola_ also living in Brazil, is yellow above, with
brown dots; the sides of the belly and thighs have {198}transverse bluish
bars, the under parts are whitish. Its size is under 2 inches. Goeldi has
often found it in the sheaths of decaying banana-leaves. It glues the lumps
of eggs on to the edges and to the inside of the withered leaves, where
even during the hot hours of the day sufficient coolness and moisture are
preserved. These lumps are enveloped in a frothy substance, in which the
nearly metamorphosed tadpoles can be watched wriggling. If these are put
into water, all will die in a few hours.
_H. polytaenia_ deposits its eggs in free lumpy masses on water-plants. It
is a small creature, little more than 1 inch in length, light olive above,
with numerous brown parallel longitudinal bands on the body and limbs. A
dark, white-edged band extends from the nose along the side of the body.
The heel has a short flap of skin. The male has an internal vocal sac.
_H. goeldii_ is a most interesting form, leading to the allied genus
_Nototrema_. Boulenger[87] has described a female which was captured by
Goeldi in January on the Serra dos Orgãos. It is about 1½ inch long. The
whole surface of the back is occupied by a layer of twenty-six pale yellow
eggs which are 4 mm. in diameter. The skin of the back is expanded into a
feebly reverted fold, which borders and supports the mass of eggs on the
sides, thus suggesting an incipient stage of a dorsal brood-pouch. Owing to
the great amount of yolk, the young are probably able to remain upon the
mother until they are nearly metamorphosed.
[Illustration: FIG. 38.–_Hyla goeldii._ × 1. Female with eggs in the
incipient dorsal brood-pouch.]
_H. coerulea_ s. _cyanea_ is one of the largest Australian green
tree-frogs, ranging from the South to the very North of Australia. The
discs are as large as the fully-exposed tympanum. There is no projecting
rudiment of the pollex, but a slight cutaneous fold borders the inner side
of the tarsus. The skin is smooth and shiny, always a little moist, and
studded with numerous rather large pores on the nape and shoulders; this
somewhat thickened region forms a prominent fold which begins behind the
eyes. The belly and the under parts of the thighs are granular as in most
Hylidae. The male has an internal vocal {199}sac; and during the breeding
season, which seems to occur during our autumn and winter, develops brown
rugosities on the inner side of the first finger. The tongue is round,
slightly notched behind and free enough to be protruded a little.
[Illustration: FIG. 39.–_Hyla coerulea._ Australian Tree-frog (from
photographs). Length of the large specimen 4.2 inches. The upper right
specimen with vocal sac inflated.]
The alternative specific names are most unfortunately chosen, as they apply
only to spirit-specimens. During life this tree-frog exhibits a
considerable amount of colour-changes. The normal colour is bright green
above, white below. A conspicuous feature of this species is the frequent
occurrence of white specks or spots, which are probably due to the
deposition of guanine, a peculiar white colouring matter. The spots appear
in any part of the green skin, and are quite irregular in their
distribution. Sometimes they remain for weeks in the same place, or they
disappear after a few days and others appear. They are in no way connected
with the shedding of the skin, nor do they indicate ill-health. _H.
coerulea_ lives well in confinement, and becomes tame enough to take food
from one's fingers, even when sitting upon the hand. Some of mine took to
living during the daytime in a small box, preferring a crowded condition in
companionship with {200}Natterjacks. Others squeeze themselves into the
most uncomfortable cracks, while others again prefer the broad leaves of
_Philodendron_. A favourite place for two or three at a time is the
funnel-shaped spaces formed by _Bromelia_-plants. Those specimens which are
hidden in the box or in the hollows of rotten stumps are, almost without
exception, dull, very dark brownish olive, while those on the Bromelias
assume exactly the sombre dull green of its leaves. Lastly, those which sit
in the light, exposed places, no matter if upon a leaf, on a white stone,
or upon a board, are emerald-green, especially beautiful on hot, sunny
days;–and they are not always averse to the full glare of the sun. When
squatting upon a flat surface, such as a broad leaf, they tuck the
fore-paws under the head like a cat, and with half open eyelids, the pupil
contracted to a tiny slit, so that the golden iris is exposed, they remain
motionless during the day. They take food when offered, but at night they
roam about, either hopping on the ground, or making enormous leaps from
leaf to leaf, sometimes deliberately stalking some choice insect, and
patiently climbing up a stem, hand over hand. At night their whole aspect
is changed. The colour is saturated green, the eyes are transformed into
round, projecting shiny black beads, and the head is erect. The ludicrously
dreamy, complacent look has given way to wide-awake alertness. They take
all kinds of living food. When they find an earthworm, they first look at
it, bending the head sharply down, lift themselves upon the fore-limbs and
then pounce upon it, nipping the prey with the jaws, and then poking it
down deliberately with the hands. Cockroaches are simply lapped up, and
disappear in the twinkle of an eye. Mealworms, wood-lice, butterflies and
moths, flies and spiders are taken. The stomach of a specimen in the
Dresden Museum, from the Aru Islands, contained some four or five young
freshwater Crustaceans of the genus _Sesarma_. They fortunately do not
molest smaller frogs of their own kind and of other species. Like many
Amphibia they like a change of diet, and ultimately refuse their food if it
is unvaried. To my surprise my largest specimen, which measures a little
more than 4 inches, takes snails, _Helix virgata_, half-a-dozen at a time,
and on the following day, not during the night, vomits the sucked-out
shells in a lump, like the pellets of birds of prey. During this rather
painful-looking procedure the whole tongue and about half an {201}inch of
the everted gullet are protruded out of the mouth, and are then slowly
withdrawn. After having roamed about all night, they return to their
respective resting-places, where each individual is sure to be found in
exactly the same spot, day after day. They do not mind being looked at, but
if taken up and put back they avoid that place for perhaps a week, taking
shelter somewhere else.
Both sexes have a voice, but that of the female is only a grunting noise,
while the male inflates its gular sac and sends forth a sharp cracking
sound, which can turn into a regular bellowing like the gruff barking of an
angry dog. They bellow at any time of the year, frequently on the approach
of a shower or during a thunderstorm. Certain noises will also induce them
to bark. The rattling produced by the syringing of the greenhouse, sawing
of wood, hammering, the raking of the gravel, or even the scraping of boots
on the gravel-path is liable to start one of the males, and the others are
sure to chime in.
According to Fletcher, _H. coerulea_ and _H. aurea_ lay their eggs in round
white frothy patches, which float in the water, chiefly during the months
of August and September; but when the spring months are very dry, the
pairing is delayed until the following January. Several other Australian
species of _Hyla_, e.g. _H. ewingi_, spawn at any time of the year if the
conditions are favourable. They attach their eggs to submerged blades of
grass or to twigs.
_H. aurea_ is one of the commonest and most beautiful species, occurring
throughout Australia and Tasmania, excepting of course in the large
deserts. It has the appearance and restlessness of a water-frog, is not
unlike _Rana esculenta_, and grows to about three inches in length. The
tympanum is very distinct, but rather small. The fingers are without a
pollex-rudiment, the tarsus has a fold along its inner edge. The adhesive
discs are decidedly small. The male has two internal vocal sacs, which
bulge out sideways. The skin is smooth and shiny. The under parts are
white; the upper parts are, speaking generally, a mixture of blue and
olive, with blue or brown spots, but spirit-specimens give no idea of the
beauty which this changeable species can assume. Sometimes the same
individual is saturated blue and green, with several longitudinal stripes
of burnished copper along the back; a few minutes later the stripes glitter
{202}like gold, and in other moods the whole upper surface is mottled blue,
green, and brown. My specimens often went into the water and did not climb.
The food is said to consist chiefly of other small frogs in preference to
insects.
_Nototrema_ differs from _Hyla_ in so far as the female has a pouch on the
back for the reception of the eggs. This bag is formed by an infolding of
the skin; it opens backwards in front of the vent, it has a sphincter and
is permanent, although it distends to larger dimensions when in use. An
initial stage of such a pouch is possessed by _Hyla goeldii_ (Fig. 38). The
pupil is horizontal, the tongue can be protruded but little; the tympanum
is free, and the adhesive discs of the fingers and toes are well developed.
These "marsupial frogs," of which about half-a-dozen species are known,
live chiefly in the tropical forest-region of South America, notably from
Peru to Venezuela.
_N. marsupiatum_ is green with darker blue-green spots, or with
longitudinal patches which are each surrounded by a whitish or yellow seam
of little dots. The limbs have cross-bars. Total length about 2½ to 3
inches. The eggs of this species are comparatively small and numerous. The
very small tadpoles have no external gills, and escape from the pouch to
finish their metamorphosis in the water.
_N. testudineum_, about 3 inches in length, is of a uniform lead-colour,
but is lighter beneath. The skin of the back is studded with stellate
calcareous deposits, a peculiarity which is alluded to in the specific
name.
_N. oviferum_ is brown above, with darker patches on the sides of the body
and with cross-bars on the limbs. The last two species and _N. fissipes_ of
Brazil, near Pernambuco, carry their young in the pouch until the
metamorphosis is completed. This long nursing-period necessitates a great
amount of food-yolk in the eggs, and this enlargement in turn implies a
considerable reduction in their number. The female's load consists of about
fifteen eggs only, but these are of a great size, namely one-eighth of the
length of the mother's body.
_N. pygmaeum_, in Venezuela, is a tiny creature. The female, just one inch
in length, carries only from four to seven eggs. It looks then "as if it
carried a sac filled with a few gigantic balls." This species is further
worthy of note on account of the opening of the brood-pouch, which is a
longitudinal slit, whence a kind {203}of thin and slightly elevated ridge
or fold of the skin extends on to the neck. The suggestion, that this seam
is burst open, in order to set the full-grown young free, instead of their
passing through the existing opening, is scarcely credible.
These Neotropical tree-frogs seem to be rare, and females with embryos are
of course still more uncommon, so that the best account of their structure
is still that given by Weinland[88] of _N. oviferum_. How the eggs get into
the pouch has not yet been observed, but it is most likely with the help of
the male, immediately after fertilisation. The pouch forms two blind sacs
which extend forwards over the sides of the back. The eggs are large, 1 cm.
in diameter, and the enclosed embryos, or rather tadpoles, had a length of
15 mm., with a large amount of yolk still contained in the spirally wound
intestine. The first two gill-arches carried each a double thread, which
expanded into a funnel-shaped membrane, not unlike the flower of a
_Convolvulus_, and furnished with a capillary network; the stalk contained
muscular fibres. These most peculiar structures are of course the much
modified external gills. Those of _N. testudineum_ and _N. cornutum_ are
likewise bell-shaped.
_Hylella_ differs from _Hyla_ chiefly by the absence of vomerine teeth, and
consists of about half-a-dozen small species, about one inch in length. The
fact that two species live in Queensland and New Guinea, while the others
are natives of tropical America, suggests that this genus is not a natural
but an artificial assembly, an instance of convergent evolution.
_Phyllomedusa_, composed of about one dozen species of tree-frogs, is
characterised by the vertically contracted pupil, large adhesive discs, and
the opposable nature of the inner finger and of the hallux, the last joints
of which are like thumbs. The sacral diapophyses are strongly dilated. The
range of the genus extends from tropical Central America to Buenos Aires.
Most of the species are about 2 inches in length, blue-green to violet
above, with white purple-edged patches on the sides of the body; the under
parts uniform white, or with purple or brown patches. The male has a
subgular vocal sac. Some have more or less distinct parotoid glands. _Ph.
dacnicolor_ of Mexico is uniform green above, whitish below, and attains a
size of more than 3 inches. In _Ph. bicolor_ of Brazil, the skin of the
upper {204}parts is studded with calcareous deposits, and the parotoids are
large. It is blue-green above, purplish white below, the sides of the body
and limbs with white purple-edged spots.
_Ph. hypochondrialis_ has been found breeding freely in the Paraguayan
Chaco by Budgett,[89] from whose account the following notes have been
extracted. This brilliantly coloured frog is green above, which colour may
become brown-grey or bluish at will; below, white and granular. The flanks
are scarlet, with black transverse bars, and the plantar surfaces are deep
purplish black. Total length about 1½ inch.
The "Wollunnkukk," as it is called by the Indians, from the call of both
male and female at pairing time, is extremely slow in its movements, and is
active only at night. At this time, if it is seen by the aid of a lantern
as it slowly climbs over the low bushes and grass, it is very conspicuous.
In the daytime, however, nothing is seen but the upper surface of the body
as it lies on the green leaf of a plant. It has a remarkable power of
changing its colour to harmonise with its surroundings, and can effect a
change from the brightest green to light chocolate in a few minutes. The
skin is also directly sensitive to light; for if the frog is exposed to the
sun while in a tuft of grass in such a way that shadows of blades of grass
fall across it, on removal it will be found that dark shadows of the
grasses remain on the skin, while the general colour has been raised to a
lighter shade. Its food consists largely of young locusts. The ovaries on
each side are divided into five distinct clusters. The rectum has a large
saccular diverticulum, which is very heavily pigmented.
In the breeding season–December to February–this beautiful frog collects in
considerable numbers in the neighbourhood of pools. During the night-time
they call incessantly to one another, and produce a sound as of a dozen men
breaking stones, well imitated by the native name.
The eggs are enclosed in batches in leaves near the margin of the water.
Budgett has been able to watch the whole process of oviposition and
fertilisation. He found, at 11 P.M., a female carrying a male upon her
back, wandering about in search of a suitable leaf. At last the female,
climbing up the stem of a plant near the water's edge, reached out and
caught hold of the {205}tip of an overhanging leaf, and climbed into it.
Both male and female held the edges of the leaf together, near the tip,
with their hind-legs, while the female poured her eggs into the funnel thus
formed, the male fertilising them as they passed. The jelly in which the
eggs were laid was of sufficient firmness to hold the edges of the leaf
together. Then moving up a little further, more eggs were laid in the same
manner, the edges of the leaf being fastened together by the hind-legs, and
so on up the leaf until it was full. As a rule, two briar-leaves were
filled in this way, each containing about 100 eggs. The time occupied in
filling one leaf was three-quarters of an hour.
Development proceeds rapidly. Within six days the embryo increases from the
2 mm. of the egg-diameter to 9 or 10 mm. When it leaves the leaf it is a
transparent glass-like tadpole, whose only conspicuous parts are the eyes.
These are very large and of a bright metallic green colour, so that when
swimming in the water all that is seen is a pair of jewel-like eyes. The
newly-hatched tadpole has also a bright metallic spot between the nostrils
somewhat in front of the pineal spot. This is the point which touches the
surface of the water when the tadpole is in its favourite position. Whether
it is a protective coloration, or some mechanical arrangement for holding
the surface, Budgett could not make out.
The egg contains a great amount of yolk; the rest of the jelly-like
contents of the egg becomes fluid, so that towards the end of embryonic
life the larva comes to lie quite freely within a membranous capsule. The
external gills appear on the third day, and reach their greatest size on
the fifth, when these bright red filamentous organs extend beyond the vent.
By the time the tadpoles are ready to be hatched these gills have quite
disappeared, there is a median spiracle, and the lungs are shining through
the transparent body-wall. Five weeks later, _i.e._ six weeks after the
eggs were laid, the tadpole is 8 cm. long, glossy green above, rosy and
silvery below, and the hind-limbs protrude. The young frog at the close of
its metamorphosis is two-thirds the length of the adult, and at this time
acquires the red flanks barred with black.
The first account of the breeding of _Phyllomedusa_ was given by v.
Ihering[90] concerning _Ph. iheringi_ of Southern Brazil.
{206}"_Phyllomedusa_ does not lay its eggs in the water, although the larva
develops in that element, but in the open air in masses 50 millim. long by
15-20 broad, between leaves hanging over the water. Willows are frequently
used for that purpose. The egg-mass contains rather large white ova,
wrapped up between two or three leaves in such a way as to be completely
enveloped save an inferior opening. My attempts at rearing the eggs failed
owing to the leaves drying up; but I am assured that the tailed larvae may
be seen wriggling in the gelatinous mass. As at a later period the latter
is found empty, we must infer that the larvae drop into the water below.
The eggs are found only on plants hanging over stagnant water."
[Illustration: FIG. 40.–A branch with eggs of _Phyllomedusa iheringi_, × 1,
enveloped in the leaves. (After v. Ihering.)]
"The adult animal is a stupid creature, and will let itself be taken
without attempting to escape. Their moderately loud voice resembles
somewhat the sound produced by running the finger nail over the teeth of a
comb. Only during the breeding season, in the month of January in Rio
Grande do Sul, do these frogs make their appearance; at other times not one
is to be seen, probably because they establish themselves high up in the
trees."
_Agalychnis_, with two species in Central America, is practically like
_Hyla_; but the pupil is vertical, and the tongue is extensively free
behind.
_Nyctimantis_ differs from either by its round tongue, which is not nicked
behind, and is almost completely adherent, much resembling that of the
Discoglossidae. The sacral diapophyses are but slightly dilated. The only
species, _N. rugiceps_, lives in Ecuador, and grows to nearly three inches
in length. The head is large and rough owing to the skin being involved in
the cranial ossification. It is further peculiar in its coloration, the
under parts being chestnut-brown instead of whitish. The upper parts are
olive-grey or brown.
The following four genera, each represented by one or two species
{207}only, much resemble each other in the curious shape of the head, which
forms a flat projecting snout, used probably for digging in rotten wood in
search of insects. There is a peculiar degradation in the extent of
dentition of the palatal region. _Diaglena_ and _Triprion_ are the only
Hylidae which possess a longitudinal row of parasphenoid teeth. _Diaglena
petasata_ of Mexico and _D. jordani_ of Ecuador have, moreover, a
transverse row of teeth on the palatine bones in addition to those on the
vomer.
_Triprion petasatus_ of Yucatan has parasphenoid and vomerine teeth. The
head is a bony casque, with strong superciliary ridges, the skin being
extensively ossified. The mouth forms a flat snout, owing to the long
projection of the upper over the lower jaw. The skin of the back is smooth
brown with darker spots; the under parts are uniform whitish. The male has
a subgular vocal sac. Like _Diaglena_ and _Corythomantis_ they possess
adhesive discs on the fingers and toes, and climb trees. The total length
of this curious creature is 2 inches.
_Corythomantis greeningi_ of Brazil has a similar head. The vomers alone
carry teeth, besides of course the maxillae. The pupil is rhomboid. The
tongue, as in the two previous genera, is roundish, scarcely free. General
colour above olive, with darker freckles; the sides are studded with
whitish tubercles; the under parts are whitish. The male is devoid of vocal
sacs. Total length 3 inches.
_Pternohyla fodiens_ of Mexico approaches the previous three genera by the
curious shape of the head and prominent upper jaw, although these features
are not so exaggerated. The dentition agrees with that of _Corythomantis_
and other normal tree-frogs. The fingers and toes are not provided with
discs, in conformity with the burrowing, not climbing, habits of this
creature. The next following three genera connect the Hylidae with the
Cystignathidae. The sacral vertebrae are but slightly dilated.
[Illustration: FIG. 41.–Head of _Corythomantis greeningi_. × 1. (After
Boulenger, _Cat. Batrach._)]
_Acris._–The adhesive discs are very small, the tympanum is indistinct. _A.
gryllus_, the only species, inhabits the greater part of Eastern and
Central North America, extending northwards into Canada. It attains a
length of 1½ inch. The coloration is very changeable, in adaptation to the
surroundings. As {208}a rule it is brown, with a more or less reddish or
grey ground-tone, ornamented with dark brown or blackish irregular,
longitudinal patches,one of which is bordered with light green,and there is
often a light vertebral streak. The legs are cross-barred, the under parts
are whitish brown and yellowish. The male has a subgular vocal sac, and its
most remarkable feature is the voice, which closely resembles the noise of
a cricket or of certain grasshoppers. Holbrook describes it as a merry
little frog, constantly chirping like a cricket, even in confinement. It
frequents the borders of pools, and is often found on the leaves of aquatic
plants, rarely on the branches of such low shrubs as overhang or dip into
the water. When disturbed it takes long jumps, and hides at the bottom of
the pond. Insects are secured by leaps. It can easily be domesticated, and
takes food readily from the hand. Sprinkling them with water never fails to
make them more lively and noisy. Appearing in April in great numbers, they
are said to vanish early in the autumn for hibernation. The tadpoles are
metamorphosed by the end of August.
_Chorophilus._–The fingers and toes are provided with very small adhesive
discs. The sacral diapophyses are very slightly dilated. About seven
species occur in North America, chiefly in the Southern States, one, _Ch.
cuzcanus_, in Peru. _Ch. ocularis_ is the smallest of the frog-kind known,
and lives in South Carolina, frequenting damp places, the vicinity of
stagnant pools, water-plants or low shrubs, for instance the "myrtle,"
_Myrica cerifera_. I once had two of these tiny creatures less than
three-quarters of an inch in length. They were very active, and took
surprisingly long leaps, jumping distances of 2 feet, but could not be kept
through the winter, although they took minute insects readily enough. The
head is narrow, long and pointed; the upper parts are of a rich
chestnut-brown with a bronzy gloss. The upper jaw is white; a black band
extends along the sides of the head and body. The under parts are yellowish
white.
_Ch. ornatus_ is another inhabitant of the South-Eastern States; its name
refers to the dark brown patches on the back and sides, bordered with
golden yellow, upon a reddish-brown ground-tone, while the under parts are
silvery white with fine grey spots. This frog, a little more than one inch
in length, lives on land in dry places, preferably in corn-fields, has no
voice, and, except during the pairing season, carefully avoids the water.
{209}_Thoropa._–The fingers and toes are free, the tips simply swollen and
not dilated into discs. Closely allied to _Chorophilus_. _Th. miliaris_, of
Brazil, the only species, has very long toes. The head is broad and flat.
The upper, nearly smooth surface of the body is flesh-coloured, with brown
marblings; the limbs are cross-barred; the under parts whitish, granular on
the belly. The male is devoid of vocal sacs. The total length may be 2
inches. Hensel has published the following notes of this species, under the
name of _Hylodes abbreviatus_. The tadpoles are quite flat, their bellies
forming a kind of sucking disc, so that these creatures, even before the
appearance of the hind-limbs, can quickly wriggle up vertical walls of
stones, provided these are covered with a little water. In correlation with
this habit, the root of the tail is not compressed laterally, but is as
broad as it is high, and the usual vertical fin is restricted to its distal
third. On the proximal portion of the tail the ventral fin is flattened and
broadened out so as to form almost the continuation of the peculiar
disc-like belly. The anal opening is not a projecting tube, but is a
flattened transverse slit.
FAM. 5. CYSTIGNATHIDAE.–This is one of the largest families, and also one
of the least satisfactory. Its numerous members, more than 150, exhibit
such a versatility in adaptation to circumstances (there are aquatic,
terrestrial, arboreal, and burrowing species), with a corresponding
development or loss of anatomical characters which we should like to rely
upon as taxonomic marks, that the numerous genera not only run into each
other, but also get entangled with those of other families. In fact the
whole family is ill defined. It can be characterised as follows:–The
shoulder-girdle is arciferous; the sacral diapophyses are cylindrical or
but slightly dilated; the metasternum has either a bony style or it forms a
cartilaginous plate; the terminal phalanges, although they sometimes carry
adhesive discs, are never claw-shaped.
The last statement is, of course, intended to separate the Cystignathidae
from the Hylidae, of which, however, the three genera _Thoropa_,
_Chorophilus_, and _Acris_ stand on debatable ground (cf. p. 186, Hylidae),
while, on the other hand, most of the Australian genera, notably
_Chiroleptes_, have unmistakably dilated sacral diapophyses. The difference
from the Pelobatidae can in this case be one of degree only.
{210}The Cystignathidae may be said to represent the Ranidae in Notogaea.
Some of them can be distinguished from the true, typical frogs solely by
the arciferous type of the shoulder-girdle and sternum. There is in both
families the same adaptive versatility, the same amplitude in the formation
of the fingertips, the occasional slight dilatation of the sacral
diapophyses, the same range in the configuration of the omo- and
meta-sternum. In fact, young Ranidae, before the firmisternal character is
assumed, are indistinguishable from Cystignathidae, and the latter would
turn into Ranidae if they could be induced to consolidate their sternal
apparatus.
The geographical distribution of the Cystignathidae is suggestive of their
being an old family, most of whose members have reached a high stage of
morphological development. The overwhelming majority inhabit the
Neotropical region, a few forms extending into tropical Central America and
into the Antilles; the rest, some twenty species only, are confined to the
Continent of Australia and to Tasmania.
The family name is rather a misnomer. It is taken from the genus
_Cystignathus_, which is, or rather was, characterised by the peculiarly
broadened lower jaw, hollowed out by the vocal sacs; but this generic name
had to give way to that of _Leptodactylus_, in obedience to the often
senseless rule of priority. The family is composed of three subfamilies.
SUB-FAM. 1. HEMIPHRACTINAE.–Teeth are carried by both jaws, the vomers and
the palatine bones; or by the palatines and parasphenoids in _Amphodus_.
The vertebrae are opisthocoelous, devoid of ribs, and the sacral
diapophyses are not dilated. The shoulder-girdle and sternum are strictly
arciferous. The omosternum is very much reduced; the metasternum forms a
cartilaginous plate. The tongue is slightly free behind. The tympanum is
distinct. Three genera, with eight species, all inhabitants of South
America.
_Hemiphractus._–The head is large; the upper surface of all the cranial
bones appears pitted, owing to most of the covering skin being involved in
the ossification. The temporal fossa is bridged over or roofed in by the
fronto-parietal and the squamosals, so that the orbit is completely
encircled by bone, as in _Pelobates cultripes_. The terminal phalanges are
simple and are not dilated into discs. The teeth of the lower jaw are
{211}very small and numerous. The tongue is round and very small. _H.
scutatus_, the only species, living in Ecuador and Colombia, is a frog-like
creature, with a large helmet-shaped head. Total length 2½ inches.
_Ceratohyla_ has the same kind of helmet-shaped head, and the orbit is
likewise enclosed by bone, but the terminal phalanges are claw-shaped and
carry regular adhesive discs. This genus, the five species of which live in
Ecuador, bears undoubted resemblances to the Hylidae. In _C. proboscidea_
the upper eyelid is produced into a little upright fold, as in
_Amphignathodon_ and some species of _Nototrema_ and _Ceratophrys_ among
Cystignathidae. The snout is produced into a long, compressed, bifid
appendage, and the heel carries a triangular flap. In _C. bubalus_ the
partly ossified helmet sends out a pair of diverging processes, formed by
the squamosals, extending backwards and sideways from the concave and
ridged interorbital spaces. The tip of the snout and the tips of the
divergent horns form an equilateral triangle, and the whole head bears a
striking resemblance to some of the fossil Reptiles from the Elgin
Sandstone, e.g. _Triceratops_. Total length 3 inches.
_Amphodus wucheri._–The only species of this genus has been found near
Bahia. It has teeth on the palatine bones and five series of small teeth on
the parasphenoid, but none on the vomers. The teeth of the mandible number
about eleven on each side and decrease in size towards the symphysis. The
tympanum is distinct; the heart-shaped tongue is free behind. The cranial
bones are only slightly pitted. The skin is smooth above, chocolate-brown,
spotted with yellow, and with a yellow band on the sides of the body
beginning with the upper eyelid and ending in a broad patch above the vent.
The under parts are yellowish white.
SUB-FAM. 2. CYSTIGNATHINAE.–The upper jaw alone is provided with teeth.
Vertebrae procoelous. The twenty-seven genera of this sub-family have been
arranged in the following key, merely for convenient determination.
I. American genera.
_A._ The metasternum forms a cartilaginous plate without a narrow
handle. The pupil contracts into a horizontal slit.
_a._ The terminal phalanges are bifurcated, Y-shaped, and provided
with large discs; the tympanum is distinct; the omosternum is absent
.......... _Centrolene geckoideum_, Ecuador.
{212}_b._ The terminal phalanges are T-shaped and carry discs. The
omosternum is cartilaginous.
α. Discs divided by a dorsal groove.
With vomerine teeth .......... _Elosia_, 3 species in Brazil.
Without " .......... _Syrrhopus_,[91] 9 species, South
America.
β. Discs undivided.
With vomerine teeth .......... _Hylodes_, p. 214.
Without " .......... _Hylopsis._
_c._ Terminal phalanges simple, pointed, or with very small discs.
First finger opposed to the others .......... _Pseudis_, p. 213.
_d._ Terminal phalanges simple, without discs.
α. Tympanum hidden. A large, flat gland on each side of the body
.......... _Cyclorhamphus fuliginosus_, Brazil.
β. Tympanum distinct. Head rough, entirely bony. ..........
_Calyptocephalus_, p. 215.
γ. Tympanum hidden or absent. Tongue roundish, not nicked, free
behind. Toes webbed. .......... _Telmatobius_, 6 species in Western
South America.
δ. Tongue heart-shaped, free. Toes webbed. ..........
_Ceratophrys_, p. 215.
ε. Tongue round, free behind. Toes webbed. With two tooth-like
projections in the lower jaw. .......... _Lepidobatrachus_, p. 218.
ζ. Tongue entire, or slightly nicked, free behind. Toes free.
.......... _Borborocoetes_, 11 species in Western South America.
η Tongue entirely adherent Tympanum distinct. .......... _Zachaenus
parvulus_, Brazil.
_B._ Metasternum with a bony style.
_a._ Pupil horizontal
α. Terminal phalanges T-shaped, with discs. Tympanum distinct.
.......... _Plectromantis_, 2 species in Western South America.
β. Terminal phalanges simple; tips not dilated into regular discs.
1. Tympanum distinct.
Sacral diapophyses slightly dilated. .......... _Edalorhina_, 3
species in Ecuador and Peru.
Sacral diapophyses not dilated. .......... _Leptodactylus_,
p. 218.
2. Tympanum indistinct or hidden, _Paludicola_, p. 220.
_b._ Pupil vertical. Terminal phalanges simple and not dilated.
Chili.
α. Tongue slightly nicked .......... _Limnomedusa macroglossa._
β. Tongue entire, but free behind. Digits very long. ..........
_Hylorhina silvatica._
II. Australian genera. The terminal phalanges are simple and not dilated.
The omosternum and metasternum are cartilaginous, the latter forming a
plate, semi-ossified only in _Heleioporus_.
{213}_A._ Pupil contracted into a horizontal slit.
_a._ Omosternum rudimentary. Vomerine teeth present.
α. Tympanum distinct .......... _Phanerotis fletcheri._
β. Tympanum hidden .......... _Cryptotis brevis._
_b._ Omosternum present. Vomerine teeth vestigial. ..........
_Crinia_, 4 species.
_c._ First finger opposed to the others .......... _Chiroleptes_,
p. 221.
_B._ Pupil contracted into a vertical slit.
_a._ Omosternum rudimentary. Vomerine teeth absent. ..........
_Hyperolia marmorata._
_b._ Omosternum fully developed. Vomerine teeth present.
α. Tympanum distinct. Toes webbed. .......... _Mixophyes
fasciolatus._
β. Tympanum hidden. Toes webbed. .......... _Heleioporus_, p. 222.
γ. Tympanum indistinct. Toes free or slightly webbed. ..........
_Limnodynastes_, p. 222.
_Pseudis_, widely distributed over South America, consists of four species
which have the appearance of long-legged frogs. The fingers, of which the
first is opposed to the others, are free; the long toes are fully webbed.
The tympanum is exposed.
_P. paradoxa_ is absolutely aquatic, floating in pools, and is extremely
shy. In life it is most beautifully coloured with bronze, bright green, and
black markings above; underneath it is shiny yellow, with brown spots on
the body and stripes on the thighs. Within a few minutes after death all
the brilliant colours of the smooth skin of the back turn into dull uniform
brown, with indistinct darker spots. Total length of the adult from 2 to 2½
inches. The specific name refers to the peculiar shape and monstrous size
of the larva or tadpole.
One of the larvae described and figured by Parker measures 10⅓ inches in
length, the head and body taking up 3⅓ inches. The spiracle lies on the
left side and the hind legs are ½ inch long, just breaking through the
skin. The vent is median. The huge tail is very thick and muscular, and is
furnished with a high, irregularly shaped dorsal and ventral fin, the whole
organ measuring 4 inches dorso-ventrally. Another larva, or rather tadpole,
in the national collection is older, and although still very large, namely,
7 inches long, has fully developed hind-limbs 3 inches long; the fore-limbs
are less than half that size, the left protrudes through the spiracle,
while the right has broken through the skin. The dorsal and ventral fins of
the tail have much shrunk; the whole organ, 5 inches long, is gradually
tapering to a point like the tail of ordinary tadpoles. By the time that
the {214}tadpole is nearly ready to leave the water, its whole bulk is
reduced to less than one-fifth that of the largest tadpole. It measures
from snout to vent only 1½ inch (in the 7-inch tadpole this distance is
fully 2 inches), and the tail, devoid of fins, is reduced to 2 inches in
length. Instead of the solitary left spiracle there are now two, one on the
ventral side and a little in front of the base of each arm, the border of
each hole being continued by a peculiar semilunar fold.
[Illustration: FIG. 42.–_Hylodes martinicensis._ 1, an egg with embryo
about seven days old; 2, another, twelve days old; 3, the young Frog just
hatched; all × ¾; 4, adult male × 1. (After Peters.)]
_Hylodes._–The numerous species, nearly fifty, of this tropical American
genus exhibit several anatomical differences. The tympanum is sometimes
indistinct or hidden, in which case the Eustachian tubes are generally very
narrow. The fingers are free, and carry discs, like the toes, which are
sometimes slightly webbed. The males have a subgular vocal sac, producing a
loud, or whistling, voice. The general appearance is that of land- and
tree-frogs; the size is small, mostly between 1 and 2 inches.
_H. martinicensis_ is about 1½ inch in length. The ground-colour is pale
yellow-grey, with a large brown patch on the nape, which colour is
continued over the back in the shape of more or less coherent or dissolved
patches. A dark brown stripe runs along the middle of the sides. The limbs
are barred with brown, the under parts are whitish. This species, known by
the vernacular name of "_coqui_" inhabits many of the West Indian islands,
_e.g._ Barbadoes, Martinique, Porto Rico, and Hayti. It has become famous,
as it was the first instance known of a frog which undergoes its whole
metamorphosis within the egg. The pairing takes place on land, in the
months of May and June, when the female lays about twenty eggs, which are
enveloped in a foamy mass and glued on to a broad leaf, or hidden in the
axillae of Iridaceous plants. The mother seems to remain in the
neighbourhood watching the eggs, which are {215}large, measuring 4-5 mm. in
diameter. Dr. Gundlach, a resident in Porto Rico, was one day, in the month
of May, attracted by sounds like those of a young bird, and found three
males and one female of this species sitting between two large leaves of an
orange-tree. He put them all into a glass vessel and soon saw a pair in
embrace. The female laid about twenty-five pale straw-coloured eggs. The
embryo develops neither gills nor gill-openings, but a large
well-vascularised tail, by means of which, being immersed in the watery
fluid contained within the egg, it seems to breathe. After twenty-one days
the tadpole, having used up all the available yolk and fluid, and most of
its own tail, bursts the egg-shell and hops away as a little frog of 5 mm.
in length, but still with a stumpy white tail, which is quite absorbed
within the same day.