of Kew Gardens. It seems to have bred and vanished again.[92]
_Calyptocephalus_ is remarkable for the dermal ossification of the cranium,
which has assumed the greatest possible extent. It affords a curious
parallelism to _Triprion_ and other Hylidae, which are likewise Central
American forms. Only two species are known; _C. gayi_ of Chili, and _C.
testudiniceps_ of Panama. They are large, thoroughly aquatic creatures, 5
to 6 inches in length, with huge heads. The tadpoles grow to an enormous
size. One specimen of _C. gayi_ in the National Collection is more than 6
inches in length, the tail taking up more than half of the total: the
spiracle lies on the left side, the vent on the right, and the hind-limbs
are still half enveloped in a kind of fold of the skin.
_Ceratophrys_ is a genus of some ten toad-like species, living in South
America, from Guiana to Argentina. The generic name alludes to the peculiar
modification of the eyelid, which in most species is developed into a
triangular, upright, but flexible appendage. The head, in conformity with
the huge mouth, is very large. The tympanum is rather indistinct, sometimes
quite hidden. Several of the species have a large dorsal shield, which is
produced by a thick ossification of the cutis, but is not fused with any of
the vertebral processes. The male has a vocal sac. _C. dorsata_ s. _boiei_
of equatorial Brazil is a monster toad, reaching {216}a length of 6 inches.
The upper eyelid is transformed into a triangular horn, whence a cutaneous
ridge extends all along the side of the back, meeting that of the other
side above the vent. There is no osseous shield on the back. The tympanum
is hidden. Ground-colours, orange or green, with sharply marked dark brown
or blackish patches.
_C. cornuta_, in Northern Brazil, lacks the dorsal shield, but has horned
eyelids and a visible tympanum. Its coloration renders it one of the most
beautiful toad-like creatures known. The ground-colours are green, black
and brown, with an orange-yellow stripe over the head and back. All these
colours are most pleasingly blended and arranged in marbled patches or
stripes radiating from various centres, as, for instance, from the eyes
towards the circumference of the mouth, the slit of which they pass, the
same line of the pattern being continued upon the lower jaw. The whole
surface makes the impression of a gay but exquisitely harmonious carpet.
The under parts are yellow, inclining to white towards the middle.
[Illustration: FIG. 43.–_Ceratophrys ornata._ Horned Toad. × ¾.]
_C. ornata_ has a dorsal shield. The tympanum is just visible, and the
eyelids form only low but sharp-edged projections. This is likewise a
beautiful toad, living chiefly in Uruguay, Northern Argentina, and
Paraguay, where it is universally known as the "escuerzo," one of the
Spanish words signifying a toad. Its size rarely surpasses 4½ inches. The
ground-colours are greenish and yellow, with large dark green patches on
the back, decreasing in size on the flanks.
{217}[Illustration: FIG. 44.–_Ceratophrys ornata._ (From _Nature_.)]
Each of these insular patches is surrounded by a narrow line of white and
yellow dots, interspersed here and there with lines of rusty brown or red.
The object of this elaborate carpet-like pattern is concealment. These
toads–and this applies to all the species,–bury themselves half in the
ground, preferably in the grass, where they are well-nigh invisible. If
there is not enough green vegetation, they throw, with their feet, little
lumps of earth upon their backs, the skin of which becomes at the same time
more crinkled and assumes duller tones. There the creature lies, perfectly
concealed, betrayed only by the metallic glittering eyes, waiting for some
unfortunate creature to pass into the trap represented by the enormous
mouth, which opens and shuts with lightning-rapidity and with an audible
snap. They seem to live chiefly on frogs, and sometimes they turn
cannibals. Two specimens were brought over to me from Buenos Aires by a
friend, in a well-closed basket with moist soil at the bottom, but only one
was visible on arrival. The other was inside the {218}larger one, and could
still be felt through the soft body. This same cannibal took large-sized
frogs greedily, one or two for a meal, swallowing them whole and then
sinking back into its lair, which it scarcely ever left, except for an
occasional soaking bath in its water-pan, especially before shedding its
skin. It lived for many months in the same enclosure with a pantherine
toad, _Bufo mauritanica_, of equal bulk, until one morning I found the
Moroccan half swallowed and almost lifeless in the mouth of the American,
whence it was rescued with difficulty. It came round after a few hours, but
never fully recovered, lingering on for weeks; the skin was changed to a
lead-colour so far as it had been swallowed and partly dissolved by the
gastric juices, and soon began to develop festering ulcers.
These "horned toads" make a squeaking noise when teazed, not at all loud or
strong in proportion to their size. Ill-tempered individuals jump at their
aggressor and can inflict rather painful nips. They hibernate during the
dry season in the ground.
_Lepidobatrachus._–Large teeth in the upper jaw, and two large tooth-like
projections in the lower jaw near the symphysis. Vomer toothless. Sacral
diapophyses not dilated. Tongue round, and free behind. Tympanum distinct.
Great development of the membrane-bones on the head, and a weaker
ossification in the skin of the back, recalling that in _Ceratophrys_. The
eyes are closely set together, and the nostrils take up the most elevated
portion of the head. Pupil horizontal. The two species of this genus were
discovered by Budgett[93] in the Paraguayan Chaco. _L. asper_ lives
continually in muddy pools, floating with just the eyes and nostrils above
the surface. If disturbed it slowly sinks to the bottom, leaving no ripple.
It feeds largely on _Bufo granulosus_. Total length from about 3 inches.
The skin of the upper parts is tubercular, tough, and of a dull leaden
colour; the tips of the toes are horny. _L. laevis_ is smooth and slimy,
"with the organs of the lateral line showing clearly upon it," a feature
elsewhere known to exist in _Xenopus_ and _Leptobrachium_ only.
_Leptodactylus_ = _Cystignathus_.–Some twenty species inhabit tropical
America, from Central Mexico to Buenos Aires. The fingers and toes are not
webbed and end mostly in points; only a few species, e.g. _L.
hylaeodactylus_, having small adhesive discs. {219}The legs are long and
the general appearance is very much like that of an ordinary frog.
One of the commonest and prettiest Brazilian species is _L. ocellatus_,
which is characterised by a number of longitudinal glandular folds on the
back and flanks. The colour of the upper parts is olive-brown, that of the
prominent folds is yellowish white, interspersed with black spots. The
under parts are yellowish white, with blackish marblings on the throat. The
males have a sharp black spur on the inner carpal edge and one on the
rudiment of the thumb. Total length about 4 inches.
According to Hensel[94] the spawning takes place in Rio Grande do Sul after
hibernation. The voice of the male is then very loud, resembling the sound
made by a carpenter chopping a beam. They repair to ponds and produce a
cup-shaped puddle, about 1 foot in width, by raising a wall of mud, which
separates the inner water from that of the pond. The tadpoles remain in
this nursery until the spring-rains demolish it and set the young ones
free. Drought causes the drying up of these water-pans and subsequent
destruction of the brood.
_L. mystacinus_ is another Brazilian species, about 2 inches in length. Its
specific name refers to the dark brown stripe which runs from the tip of
the mouth through the eye to the tympanum. This species is thoroughly
terrestrial, and never enters the water. It digs a cavity, the size of an
ordinary tea-cup, under stones or rotten trunks, always in the
neighbourhood of ponds and just so high above the water that the latter can
rise up to the nest in the rainy reason. The straw-coloured eggs are laid
in this cavity, and are enveloped in a foamy, sticky mass, like the
well-beaten white of an egg. The young tadpoles seem to live on this froth
until the rains set them free. When, however, the rains delay and a drought
kills the broods of other less circumspect species, these tadpoles, still
provided with gills and long tails, remain in their moist nest or withdraw
further beneath the rotten stumps, huddled together in large numbers until
the next rainy season.
Similar nursing habits have been recorded of _L. albilabris_, which
inhabits Mexico, Cuba, and several other West Indian islands. The same
applies to _L. typhonius_. Gundlach found eggs {220}of this "Sapo" in
Puerto Rico on the 4th of November; on the 25th the young showed the first
signs of hind-limbs, on the 3rd of December of fore-limbs, and on the 7th
of the same month they began to climb out of the water.
_Paludicola_ is a semi-aquatic genus with some eighteen species, ranging
from Mexico to Patagonia and across the Andes into Chili. Some of them have
a peculiar gland on the lumbar region, or large, flat warts on the back,
sometimes arranged in longitudinal folds. The toes are slightly webbed, or
free, according to the more or less pronounced aquatic habits.
[Illustration: FIG. 45.–_Paludicola fuscomaculata_, × 1, with vocal sacs
partly filled.]
_P. fuscomaculata_, an inhabitant of Southern Brazil, Paraguay, and
Uruguay, is a short-limbed frog, with spreading slender toes and a small
head. There are shovel-shaped, black, horny tubercles on the metatarsus.
The general colour is olive above, with darker markings and confluent
white-edged spots; the limbs are cross-barred; the lumbar glands are black,
with a white margin in front. The male has a vocal sac. Budgett[95] gives
the following account of its habits:–
The peculiar cry, which is so constantly heard in the neighbourhood of
shallow pools in the Paraguayan Chaco, and resembles that of a kitten, is
produced by the alternate inflation of throat and abdomen. When fully
inflated, the frog appears to be the size of a golf-ball, but, if startled,
instantaneously shrinks to one-fifth of that size, so that it seems to have
vanished. It has also the power of ventriloquising. The food consists
largely of water-beetles. In the spawning time it was found at night
floating on the surface of pools in the distended condition, and crying to
the females in a most mournful way. On coming to the surface it fills its
lungs with a few gasps, greatly distending the walls of the abdomen, and
then drives the air into the vocal sacs, causing them to become distended
as the body collapses, and giving rise to a kitten-like cry.
The eggs are chiefly laid in January, and are found embedded {221}in a
frothy mass floating upon the surface of the water. The eggs measure only 1
mm. and are without pigment, and with extremely little yolk. The larvae
become free-swimming within from eighteen to twenty-four hours after the
first segmentation. When ready for hatching they wriggle their way through
the froth to the water below, and hang into it from the floating froth.
_P. biligonigera_ s. _notata_, in Brazil, lacks the lumbar gland, the place
of which is marked by a black spot. The upper parts are olive, with darker
marblings and a dark lateral stripe. The male has a black throat and two
external vocal sacs. Hensel found the eggs, in Rio Grande do Sul, in
September, forming a frothy mass of the size of a fist, floating between
grass upon the water near the margin.
The following three genera may serve as Australian examples, especially
since we are indebted to Baldwin Spencer for interesting observations made
on their habits in Central Australia.[96]
_Chiroleptes_, of which six species are known, is easily recognised by the
first finger, which is opposed to the others. The sacral diapophyses are
slightly dilated. The general shape is that of a thick-headed, rather stout
land-frog or of a tree-frog. The tympanum is distinct, and the toes are
only half webbed, or even less, except in _Ch. platycephalus_, in which the
toes are entirely webbed and the tympanum is indistinct. This species is
about 2 inches long, uniformly olive-green above, with a few tubercles on
the otherwise smooth skin. Other species rather resemble the European
Natterjack in coloration.
Spencer's account is as follows:–"In Central Australia _Ch. platycephalus_
seems to prefer the hard clay pans rather than sandy creeks, as the
sand-beds of the latter are too loose for the formation of the burrow. We
came across the animal first when encamped by the side of a very shallow
clay pan, the floor of which was deeply cracked with the sun's heat. Around
the edge were withered shrubs of _Chenopodium nitrariaceum_, and it was at
the base of these that the black fellows looked for the burrow. In the
hard-baked clay were imprints made by the frog as it burrowed, and about a
foot underground we came across the animal, puffed out into a spherical
shape, and just filling up a cavity, the walls of which were moist but not
wet. The ground {222}was so hard that it had to be chipped away. When one
side of the burrow was opened, the frog remained perfectly still; its lower
eyelid was drawn up over the eye and was very opaque, giving rise to the
belief amongst the blacks that the animal is blind. In the sunlight, after
a short time, it opened its eyes.
"On squeezing the body, water was forced out of the cloaca; this was
accumulated principally in the urinary bladder. On cutting the body open it
was seen that there was a certain amount of water in the subcutaneous
spaces, but that the greater portion, which caused the great swelling-out
of the body, was contained in the body-cavity itself; and it was also
observed that the lungs were considerably distended and lengthened, their
apices lying right in the pelvic region. They contained air and not water,
but their outer faces were bathed with the water in the body-cavity." The
larvae and tadpoles probably develop with extreme rapidity, soon to
aestivate as very small frogs.
_Heleioporus_ has a calcified metasternal plate and slightly dilated sacral
vertebrae. The two species have a toad-like appearance, owing to their
stout bodies, short limbs and conspicuous parotoid glands. _H.
albopunctatus_ is mottled whitish red and brown above; it extends from
Western into Central Australia. _H. pictus_ is olive, with darker
marblings, and is distinguished by a light vertebral line. It is likewise
found in Central Australia, and it extends into Victoria and New South
Wales. Spencer found it in swarms after heavy rains, the specimens being
much swollen and distended with caterpillars and beetles. They looked as if
they were simply gorging themselves with food preparatory to returning
again to their long aestivating condition.
_Limnodynastes_ is one of the commonest genera in Australia. The six
species have the habits and appearance of stout frogs or smooth toads. _L.
dorsalis_ seems to range through the whole of Australia, from east to west,
and looks like the European _Pelobates_. The skin is smooth, but with an
elongated white gland extending from beneath the eye to the shoulder, and
another glandular complex on the thigh. The upper parts are mottled
olive-brown, often with a light vertebral line. The under parts are
whitish, with brown spots. The male has a vocal sac. One of the specimens
in the National Collection contained a half-grown _Heleioporus
albopunctatus_ in its stomach.
{223}Concerning the pairing and the other habits of the Anura of New South
Wales we have some valuable notes by J. J. Fletcher.[97] He observes that
Australian frogs spawn whenever they are ready, and when the very irregular
conditions of moisture will allow it, but that they are not all ready at
the same time, _i.e._ they have no fixed period of the year.
_Limnodynastes_, _Hyla aurea_, and _H. coerulea_ deposit their spawn in the
water, in more or less irregular floating patches, which look white and
frothy. The period extends from July to May, and is at its height in August
and September; but if there is a spring-drought vigorous spawning may be
looked for about the middle of January, when heavy showers are likely to
occur. _Crinia_ and several _Hyla_, e.g. _H. ewingi_, spawn at any time of
the year. The eggs form small submerged bunches, enclosed in a transparent
jelly, attached to the blades of grass or twigs of dead branches in the
water.
_Pseudophryne_, a genus closely resembling _Crinia_, but on account of the
absence of teeth in the lower jaw relegated to the Bufonidae, spawns during
the Australian summer and autumn. The numerous ova of _P. australis_ and
_P. bibroni_ are laid separately, not in the water, but under stones, or in
the débris of reed- and grass-tussocks, on the edge of a pool.
The larvae of _Pseudophryne_ and others have often to depend upon the next
following rain, sometimes waiting for months to be released from the eggs,
wherein they have so far developed. But the tadpoles, once hatched,
probably do not bury themselves; they either metamorphose or die.
The males of _Mixophyes_ and _Hyla_, grasp the females in the axillary
region; those of _Limnodynastes_, _Hyperolia_, _Crinia_, and _Pseudophryne_
throw their arms round the inguinal or lumbar region.
For some three months during the winter, commencing about May, the frogs,
like lizards and snakes, resort to shelter under logs and stones, beneath
which they are then to be met with in a more or less sleepy condition.
During the hot and very dry periods many bury themselves in the drying-up
mud, which becomes very hard, and does not release them until the next
rains. They croak during showery times of the year. There is no evidence
that any Australian species live in the high _Eucalyptus_-trees.
{224}_Hylopsis platycephalus_, of South America, is of importance as
forming a link with the Dendrophryniscinae, owing to the very small size of
the teeth in the upper jaw. There are no vomerine teeth. The fingers and
toes are webbed, and furnished with discs. The very small omosternum and
the metasternum are cartilaginous. The pupil is horizontal. Total length,
about or under 1½ inch.
SUB-FAM. 3. DENDROPHRYNISCINAE.–The two Neotropical genera of this
sub-family are characterised by the entire absence of teeth. The toothless
condition of the upper jaw is really the sole character which separates
them from the Cystignathinae, taken as a whole. The suppression of the
tympanum and of the Eustachian tubes in _Batrachophrynus_, and the fully
webbed toes of _B. macrostomus_ indicate complete adaptation to aquatic
life. The absence of the omosternum in _Dendrophryniscus_, the absence of
vomerine teeth, the dilated phalangeal tips, the entire and quite adherent
tongue, are all features which likewise occur in some of the
Cystignathinae, and therefore cannot be urged against their affinity.
Lastly, the recently discovered South American genus _Hylopsis_ is, as
pointed out by Werner,[98] an intermediate link, owing to the extremely
small, scarcely visible teeth in the upper jaw.
_Dendrophryniscus brevipollicatus_ has been found in the neighbourhood of
Rio Janeiro. The head is depressed and triangular. The tongue is entire,
but free behind. The tympanum is suppressed. The omosternum is absent; the
metasternum forms a long bony style. The sacral diapophyses are
cylindrical. The terminal phalanges are simple, but carry dilated tips. The
first finger is rudimentary. The skin is nearly smooth, reddish brown
above, whitish below; the limbs are cross-barred.
_Batrachophrynus_ inhabits the mountains of Peru. The head is much
depressed and small, with the eyes directed upwards, as is usual in
essentially aquatic species. The tongue is large, circular, and entirely
adherent. The tympanum and the Eustachian tubes are suppressed. The
omosternum is cartilaginous, and the metasternum forms a cartilaginous
plate. The sacral diapophyses are cylindrical. The terminal phalanges are
simple, and carry no discs. The four fingers are short; the toes are
webbed. The male has no vocal sac. _B. brachydactylus_ has a {225}smooth
skin, olive-brown above with darker spots. _B. macrostomus_, 2 inches in
length, is distinguished by its larger size, and by its completely webbed
toes.
FAM. 6. ENGYSTOMATIDAE (Narrow-mouthed Toads).–_Firmisternia with dilated
sacral diapophyses._
SUB-FAM. 1. ENGYSTOMATINAE.–_Without teeth in the upper jaw._–Although
there are only about 60 species known, these have been grouped into more
than two dozen genera, many of which are represented by one or two species
only. The range of this sub-family is peculiar, namely, Neotropical and
Palaeotropical. _Scaphiophryne_ and _Rhombophryne_ are peculiar to
Madagascar; _Calophrynus_ occurs in the same island and in the Indian
region; _Xenobatrachus_, _Sphenophryne_, _Liophryne_, _Mantophryne_,
_Callulops_ and _Xenorhina_ live in New Guinea. _Breviceps_, _Cacosternum_
and _Hemisus_ are confined to Africa, while of _Phrynomantis_ two species
live in Africa, and the third in the Malay island of Amboina. Such freaks
of distribution indicate either that many of these genera are not
established upon very valid characters, or that their respective species
are instances of convergent evolution, and do not form natural genetic
groups.
Many of the members of this sub-family live upon ants and termites, and it
is a well-known fact, not restricted to the Anura, that this kind of fare
has a peculiar, modifying influence upon the structure of the mouth, teeth,
tongue, limbs, and various other organs. In the present case the tongue is
not much affected; it is, with few exceptions, more or less oval, not
nicked, but free behind; in the Indian _Glyphoglossus_ and in
_Rhombophryne_ of Madagascar only is it modified into a rather long and
grooved, almost double, apparatus.
A very common feature is the small size of the mouth and the formation of a
snout, which projects beyond the upper rim of the mouth and beyond the
nostrils. Such a prominent and pointed snout is well developed in
_Rhinoderma_, _Phryniscus_, _Calophrynus_, _Stereocyclops_, _Hypopachus_
and _Engystoma_. The mouth is very narrow in _Cacopus_, _Glyphoglossus_,
_Breviceps_, _Rhombophryne_, and _Hemisus_, all creatures which seem to be
confirmed eaters of ants and termites. However, it must not be supposed
that the mouth of all the genera is narrow, although this character, rather
marked in _Engystoma_, is now embodied in the name of the family. A
peculiar development of the palatal region {226}is possibly correlated with
this food. The palate is mostly toothless, but its skin is frequently
raised into a transverse fold, between or behind the vomers, and into a
second fold in front of the oesophagus; these folds are sometimes rather
hard and serrated or denticulated. The palatine bones carry true teeth in
_Rhombophryne_, and sometimes in _Callula_; in _Xenobatrachus_ the teeth
are reduced to two large pairs. The tympanum is usually hidden.
The shape of the body is generally very stout. The limbs are short, notably
so in _Glyphoglossus_, _Breviceps_, _Rhombophryne_, _Hemisus_,
_Stereocyclops_ and _Cacopus_. Others, for instance most species of
_Microhyla_, _Phryniscus_, _Callula_, and _Sphenophryne_, are of a very
slender build; and their limbs, instead of being short and well adapted to
digging, are long and may even be provided with typical adhesive discs,
supported by T-shaped phalanges, especially in the two genera last named,
and in _Scaphiophryne_ and _Phrynomantis_. However, none of the forms
provided with discs are known to be arboreal.
Exceptional diversity is shown in the shoulder-girdle and sternum. The
omosternum occurs only in _Rhinoderma_ and _Hemisus_. The metasternum is a
cartilaginous plate, very large in _Cacopus_, distinctly small in
_Breviceps_, and almost absent in _Hemisus_. The precoracoids and clavicles
show all stages from a well-developed condition (_Breviceps_,
_Rhombophryne_, _Hemisus_, _Rhinoderma_, _Phryniscus_ and _Brachycephalus_)
to complete absence. The circumstance that these bars are very weak in
_Melanobatrachus_, _Calophrynus_, _Scaphiophryne_ and _Hypopachus_, i.e. in
Palæo- and Neo-tropical genera, indicates a widespread tendency towards
complete suppression, a feature independently aimed at both in America
(_Engystoma_) and in the Old World.
Until we know something about the habits of the members of this much
diversified sub-family, it is idle to connect the various modifications
with each other, and thus, by correlation, to find out their meaning. Those
forms which possess well-developed discs on their fingers and toes are said
not to be arboreal. What is the true meaning of the prominent snout which
is not restricted to the digging forms? Most of the good diggers have
well-developed precoracoid bars, and the coracoids are distinctly
strengthened, but in _Glyphoglossus_ and in _Cacopus_ the precoracoids are
entirely {227}absent, and this loss is compensated for by exceptionally
strong coracoids.
On the whole, those genera are to be considered as the most primitive which
have undergone the fewest losses. Those with a complete shoulder-girdle,
with an omo- and meta-sternum and with simple phalanges, are necessarily
the older forms. One step farther back in another direction, the possession
of teeth on the palate, and on the upper jaw, leads to those genera which
have been separated off as DYSCOPHINAE, while teeth in the lower jaw
constitute the GENYOPHRYNINAE. Lastly, the firmisternal type has
necessarily been evolved from the arciferous condition, and there the two
Bufonid genera _Myobatrachus_ and _Rhinophrynus_, the former Australian,
the latter Mexican, with their narrow and scarcely overlapping epicoracoid
cartilages, seem to form a connecting link, although their ant-eating
habits, with concomitant modifications in structure, may be nothing but
cases of convergent evolution.
Key to the genera:–
I. American. _A_. with omosternum .......... _Rhinoderma_, p. 228.
_B_. without omosternum.
_a_. Pupil horizontal. Precoracoids present.
Sacrals strongly dilated. .......... _Oreophrynella._
" moderately " .......... _Phryniseus_, p. 230.
" feebly " .......... _Brachycephalus_, p. 231.
_b_. Pupil vertical.
α. Precoracoids feeble. .......... _Hypopachus._
β. " absent. .......... _Engystoma_, p. 231.
_c_. Pupil round. Precoracoids present .......... _Stereocyclops_,
p. 231.
II. Palaeotropical. _a_. Pupil horizontal.
α. Precoracoids present.
With palatal teeth. Madagascar. .......... _Rhombophryne._
Palate with dermal papillae. Africa. .......... _Breviceps_,
p. 232.
With palatal dermal folds. Madagascar. ..........
_Scaphiophryne._
With serrated palatal folds. Madagascar and India. ..........
_Calophrynus._
Palate smooth. New Guinea. .......... _Sphenophryne_ and
_Liophryne_.
β. Precoracoids absent.
Malacca .......... _Phrynella_, p. 233.
New Guinea .......... _Mantophryne._
Africa .......... _Cacosternum._
{228}_b_. Pupil vertical.
α. Precoracoids present. India. .......... _Melanobatrachus._
Africa. _Hemisus_, p. 232.
β. Precoracoids absent.
Tongue oval. India. .......... _Cacopus._
Tongue elliptical. India. .......... _Microhyla._
Tongue divided by a longitudinal furrow. India. ..........
_Glyphoglossus_, p. 233.
Fingers and toes with discs. Africa and Amboina. ..........
_Phrynomantis._
New Guinea. .......... _Callulops._
_c_. Pupil round. Precoracoids absent. Tongue round. India.
_Callula_, p. 234.
Tongue long, oval, with a deep groove. New Guinea. ..........
_Xenorhina._
_Note._–_Xenobatrachus ophiodon_, New Guinea. Palatine bones, each with
two large curved teeth. Otherwise imperfectly known.
_Rhinoderma._–Omosternum and precoracoids present. Palate without teeth.
Tympanum indistinct. Terminal phalanges simple, and not dilated. Tongue
heart-shaped, and free behind. Pupil horizontal. Habitat, Chili.
_Rh. darwini_, the only species, was discovered by Darwin, during the
voyage of the _Beagle_. Its total length is only 3 cm., or little more than
one inch. The shape is grotesque, as the skin is prolonged, beyond the very
small triangular mouth, into a false nose, _i.e._ a nose-shaped projection,
while the nostrils remain at their original place. The skin is smooth
above, granular on the under parts, and forms a triangular flap or
spur-shaped appendage on the heel. A glandular fold extends along the sides
of the body. The general colour is brown above, black below, with large
white patches, the latter colour being sometimes predominant on the throat
and chest. The male has a pair of internal vocal sacs, and the use of these
as nurseries for the young has made this species famous.
Espada[99] has given an elaborate account of this species, which lives on
the ground in shady woods. Its voice sounds like a little bell, and before
taking its short jumps, it erects itself vertically upon the hind-limbs.
The gular sac of the male opens by two slits, one on each side of the
tongue. Generally this sac does not extend beyond the middle of the chest,
but during the breeding time the eggs are put into it, whereupon it becomes
greatly distended, so much so indeed that it reaches back as far as the
groins; {229}dorsalwards around the flanks, almost to the vertebral
diapophyses; ventrally and forwards it reaches the chin. The walls of the
sac are of the same structure as the buccal lining, of which they are in
fact continuations. They adhere, at intervals, to the cutis and to the
pectoral and abdominal muscles.
The effect of the distension of the sac upon neighbouring organs is
twofold. First, the viscera are pressed back within the abdomen; this
disturbance is temporary and does not apply to all specimens; the feeding
in no way impeded. Secondly, a permanent change is produced in the
direction of the precoracoid bars, in such a way that each bar is curved
tailwards and rests with its ventral half upon the coracoid; owing to this
forcible bending the clavicles do not meet each other. There is, of course,
not so much space gained by this slight rearrangement of the
shoulder-girdle as Espada implies, but we have here, perhaps, an
illustration of direct correlation between two originally independent
organs, namely, shoulder-girdle and vocal sacs. Repeated distension of the
throat-bag during every breeding season, while the whole organisation of
the male is in a highly excitable condition, has pressed the clavicular
bars back, or rather has staved them in, and this at first pathological and
abnormal condition has at last become a fixed feature. It is to be
regretted that we know next to nothing about the habits, especially the
mode of breeding, of the other genera which likewise have reflected or very
feeble precoracoids and clavicles. Their weakness or even complete absence
must have a reason, or rather must have had a cause.
The pairing and oviposition, and the manner in which the eggs are conveyed
into the gular sac, have not yet been observed. Espada examined five males
with young, the number of which varied from five to fifteen. In one male
with eleven embryos the most developed tadpoles measured 13.5 mm. from the
snout to the end of the tail, and they were lying within the chest of the
father, the less advanced in the farther recesses of the bag. Three of the
tadpoles had already completely-formed fore- and hind-limbs, while the arms
were still hidden. The least developed were still globular, a proof that
the eggs are conveyed into the bag. Another male with fifteen embryos
looked as if it had gorged itself with the almost fully-formed tadpoles,
which measured 14 mm. They were quite irregularly distributed, and nowhere
{230}attached to the walls of the bag. None of them had horny
jaw-armaments, and not even the smallest specimens showed any traces of
gills, resembling in this latter character those in the female brood-pouch
of _Nototrema_. The intestine of the tadpoles is short and thick, coiled up
spirally and filled with yolk, certainly not with vegetable or other
foreign matter. Consequently the entire development from the egg to the
complete stump-tailed little creature is undergone within the pouch; and
this, after the young have escaped, probably shrinks back to its original
size and acts as a gular vocal sac.
_Phryniscus._–About ten species of this tropical American genus are known;
they extend from Costa Rica to Buenos Aires. They differ not inconsiderably
in various details. The tongue is elliptical, entire, and free behind. The
palate is smooth. The tympanic disc is absent. Fingers and toes more or
less webbed, sometimes with swollen tips, without, however, forming
adhesive discs. In a few species the first toe is quite indistinct. The
male has a subgular vocal sac. The mouth is small, and there is a short
snout. The general appearance varies much. _Ph. nigricans_ of Uruguay,
etc., is stout and has very short hind-limbs; the skin of the upper parts
is black, spotted with white, and covered with warts. Most of the other
species are slender, with larger hind-limbs and a perfectly smooth skin,
the coloration of which ranges from dull uniform brown, or black with
crimson markings, to bright green with purple spots. The under parts are,
as a rule, conspicuously coloured, a rare feature in Anura, the favourite
colours being orange, yellow, or even crimson, with or without black
patches.
_Phryniscus nigricans_ has been observed in Paraguay by Budgett,[100] who
gives the following account. This is a brilliantly coloured frog of
toad-like appearance, and about 33 mm. in length. The ground-colour is
black, with yellow spots or patches on the upper parts, the under parts are
black, with scarlet blotches, the palms of the hands and soles of the feet
are scarlet. At the breeding season both sexes utter a call-note which
consists of two clear musical "rings," followed by a long descending
"trill," like that of our British Greenfinch. This frog, which at ordinary
times is the slowest and boldest of frogs, is now active and excessively
shy. Swimming rapidly between the blades of grass, it climbs a {231}tuft,
and dilating its throat, repeats its call; but if in the least disturbed,
it is suddenly gone. The eggs are laid in quite temporary pools in grassy
ground, and form separate globules of jelly, which float on the surface of
the water, and are heavily pigmented. The development is excessively rapid.
The segmentation beginning at 10 A.M., they were hatched and wriggling
about by 7 A.M. the following day. They are probably washed down into
deeper pools by the retreating waters, and for this purpose the manner in
which the eggs are laid, namely, in separate globules of jelly, seems
especially suited.
_Brachycephalus ephippium_ in Brazil, the only species, is remarkable for
the development of a broad dorsal shield of bone, which is fused with the
processes of the second to seventh vertebrae, an ossification which
strongly resembles that of several species of the likewise Brazilian
_Ceratophrys_, a genus of the Cystignathinae.
_Stereocyclops_ is remarkable for the peculiar formation and protection of
the eyeballs. The anterior portion of the sclerotic is ossified into a
ring, which surrounds the transparent cornea. Another peculiarity lies in
the metasternum, which is so much broadened out that its cartilage is in
wide contact with the posterior edge of the coracoids. The epidermis is
everywhere "thickened by a chitin-like deposit." The only species, _S.
incrassatus_, found near Rio Janeiro, is an altogether aberrant creature.
Its general appearance recalls that of _Pipa_. The gape is large, with a
slightly projecting muzzle; the limbs are so short that the upper arms and
the thighs scarcely stand out from the broadened and flattened body, which
is leathery brown, with a narrow white median line extending dorsally from
the nose to the vent.
_Engystoma_, with about five species in the Southern States, Central and
South America, is the type-genus of the whole family, chiefly on account of
priority of name. It is fairly characteristic in so far as the mouth forms
a narrow, somewhat projecting snout; the precoracoids, the clavicles, and
the omosternum are absent, the palate is devoid of teeth, the lining of the
mouth forms a dermal ridge across the palate and another in front of the
oesophagus, the tympanum is hidden, the sacral diapophyses are moderately
dilated, and the tongue is elliptical and free behind. The pupil is
vertical. The fingers and toes are free, ending in slightly dilated or
blunt tips; the terminal phalanges are simple {232}and the hind-limbs are
short. The male has a subgular vocal sac.
The most northern species is _E. carolinense_, living in the Southern
United States, concealed under the bark of fallen trees or in old fences.
The skin is smooth, but forms a fold across the head, behind the eyes. The
general colour is brown, with light, whitish dots on the under parts. Total
length 1 inch.
_Breviceps_ is a South African genus with three species. The coracoids are
very strong and directed backwards, but so broadened that they form a long
and strong symphysis, touching in front that of the precoracoids, which
stand transversely and are well developed. The metasternum is cartilaginous
and decidedly small. The sacral vertebra has much dilated diapophyses and
is co-ossified with the coccyx. The general appearance is extremely stout
and short, the head being almost drawn into the nearly globular body, and
ending in a short snout with a small mouth-opening. The tongue is long and
oval, not nicked, but slightly free behind. _B. mossambicus_ is about 2
inches long, and looks like an overstuffed round bag, out of which the
short arms and legs project from the elbows and knee-joints only. The
tarsus is provided with a strong horny, spade-like tubercle, which enables
the creature to dig into the ground, and into the nests of termites, which
seem to be its chief food. Peters found this species in enormous numbers,
during the tropical rains, coming out of the ground, whither they withdraw
again completely for the dry season. The skin is smooth, reddish brown
above, with darker patches; the under parts are dull white, with a large
black patch on the throat.
_Hemisus_ is another African genus, with two species, _H. guttatum_ in
Natal, and _H. sudanense_ in East and West Africa. This genus is so
exceptional in its shoulder-girdle, that Cope separated it from all the
other Anura as a special sub-order Gastrechmia. The precoracoids are
extremely strong, and form a broad symphysis from which springs the long
cartilaginous omosternum; the coracoids are slender, very long, and
converge backwards to a narrow symphysis, and there is no metasternum. The
two symphyses are connected by a narrow cartilaginous median bar, probably
produced by the much modified epicoracoid cartilages. However, except for
the reverse development shown by the omo- and meta-sternum, it is easy to
connect this apparently quite anomalous shoulder-girdle of _Hemisus_ with
that of _Breviceps_. {233}(cf. Fig. 5, 5 and 6, p. 25). The sacral
diapophyses are slightly dilated; the fingers and toes are free and end in
points. The tongue is triangular, broader in front. The lining of the mouth
forms a transverse ridge across the palate, and another in front of the
oesophagus. The male has a subgular sac. The general shape is stout, the
head small and ending in a pointed snout. Colour brown above, with whitish
spots. Total length about 2 inches.
_Glyphoglossus_ has a peculiar tongue. It is elongated, notched behind and
in front, divided into two lateral halves by a deep groove; moreover, the
tongue is not only extensively free behind, but also slightly so in front.
The skin of the palate forms a transverse serrated ridge. The precoracoids
and the omosternum are absent; the metasternum is a well-developed
cartilaginous plate. The sacral diapophyses are moderately dilated; the
terminal phalanges are simple. _G. molossus_, the only species, is
olive-brown above, marbled on the sides; the under parts are uniformly
whitish. This creature, about 2 inches in length, looks like a roundish
bag, with a ridiculous, short face. The type-specimen, still the only one
known, was taken by Dr Theobald under the following circumstances:–"I had
halted one day within the tidal portion of the Irawaddy delta, to enable my
boatmen to prepare their dinner. One of my servants, having cooked his
rice, poured out the hot water as usual on the ground, and some of it went
down a hole that happened to be near the spot. No sooner, however, had the
hot water disappeared than out scrambled in great haste a fine
_Glyphoglossus_, only, alas! to be transferred to a collecting jar."
_Phrynella._–The tongue is heart-shaped, free behind. The palate is smooth
and toothless. The fingers and toes end in small discs, supported by
T-shaped phalanges; the fingers are free, the toes extensively webbed.
Precoracoids absent; metasternum cartilaginous. Pupil horizontal. Malay
Peninsula.
_Ph. pollicaris_ is dark olive brown above; an oblique yellow line runs
from the eye to the angle of the mouth; a pale yellow mark, across the
forehead, through the eyes, and down the sides of the body. A dark-centred
yellow patch on the anal region. The limbs are banded yellow and brown. The
under parts are brown, with paler specks, dark on the throat. Iris red
brown. The whole coloration changes considerably.
"They inhabit the hills of Perak from 3000 feet upwards, {234}and live in
holes in trees, which are so situated as to contain more or less
rain-water. They have a loud flute-like, musical note, which they utter at
irregular intervals, principally during the night. The form and size of the
hole in which they are seem to have a great deal to do with the loudness of
the note, as specimens when extracted from their holes have far more feeble
vocal powers than they had when in them. These frogs blow themselves out
with air, and look more like bladders than anything else. When inflated
they float on the surface of the water, and will remain motionless for a
long time, with legs and arms stretched out."[101]
_Callula._–The tongue is round, entire, and free behind. The palatine bones
form an acute, sometimes toothed ridge across the palate; two dermal
serrated ridges in front of the oesophagus. Fingers free, sometimes with
dilated tips, supported by T-shaped phalanges. Precoracoids and omosternum
absent; metasternum cartilaginous. Pupil round. About seven species in the
Indian region.
_C. pulchra._–The following account has been extracted from Mr. S. S.
Flower's observations:[102]–
This pretty creature inhabits most of the warm portions of the continental
Indian region, from India and Ceylon to South China and Malacca. The back
is a rich dark brown, divided from the yellow of the head by a narrow black
line which extends from eye to eye and forwards to each nostril. A
conspicuous yellow band runs from the eyes to the hind-limbs. The sides of
the body and the limbs are mottled yellow and brown. The under parts are
dirty buff; the throat of the male is black. The intensity of colouring
varies individually and from time to time, the contrast between the brown
and yellow being occasionally very brilliant. Total length up to 3 inches,
the male being the smaller sex.
"I have been told by both English and natives that this frog was unknown in
Singapore until some nine or ten years ago, when it was introduced by a
half-caste (why, it is not known), and that it rapidly spread about the
island. It is now well known as the 'Bullfrog' by the English in Singapore,
and detested for the noise it makes at night. The voice of these rotund
animals can be heard every night after heavy rain; it is {235}a deep
guttural croak, 'wau-auhhhh,' very strident and prolonged. The males croak
while floating on the surface of the water, the single vocal sac under the
mouth inflated like a globe, and the arms and legs extended. They can hop
well on land and are good swimmers. The skin is excessively slimy; the
secretion comes off profusely, and dries on the hand into a sort of white
gum, with a faint aromatic smell. This gum dissolves in hot water and
coagulates in cold. The general appearance of these frogs is very stout,
their girth being about twice the length from snout to vent. The tongue,
which is oblong in spirit specimens, in life is very elastic, assuming,
when extended, a vermiform shape and reaching about 4 cm. in length. They
appear after sunset, crawling on old wood and feeding on white ants."
SUB-FAM. 2. DYSCOPHINAE.–_With teeth in the upper jaw._
This small group of nine genera, with scarcely more than one dozen species,
all with one exception living in Madagascar, has been separated by
Boulenger from the Engystomatinae merely on account of the presence of
teeth on the upper jaw and on the vomerine margin of the palatine bones. He
himself remarks that _Calluella_ may be considered a toothed _Hypopachus_,
and _Plethodontohyla_ a toothed _Callula_. These are obvious cases of
convergent analogy. Except for the teeth, the Indian _Calluella_ would be
merged into the American _Hypopachus_, and this would present an instance
of the most puzzling geographical distribution. In the case of the other
two genera, one Indian and Malayan, the other Malagasy, no such suspicion
would arise, since there are many other instances of such a coincidence of
distribution. There is the same divergence or unsettled condition in the
modification of various parts in the Dyscophinae as in the Engystomatinae.
The precoracoid bars are weak and curved backwards, and closely pressed
against the strong coracoids, in _Dyscophus_, _Calluella_ and _Platypelis_,
while these elements are reduced to unossified bars, and the clavicular
portions completely lost, in _Plethodontohyla_ and in _Phrynocara_. The
omosternum is absent and the metasternum is small in all except
_Dyscophus_, in which both these parts are exceptionally well developed and
large, although remaining unossified. The palate of _Dyscophus_ and
_Calluella_ is provided with curious, serrated dermal folds like those
which are so common in the Engystomatinae; and well-developed discs on the
fingers and toes, supported by T-shaped phalanges, are {236}possessed by
_Platypelis_, _Cophyla_ and others. The sacral diapophyses are dilated. The
pupil is either horizontal or vertical. Those which are provided with discs
to the fingers and toes are climbers, and mostly slender and long-legged,
sometimes of very small size, for instance _Cophyla_, the body of which is
scarcely one inch in length.
The genera can be determined by means of the following key:–[103]
_A_. Pupil vertical. Palatine teeth in long transverse series.
_a_. Precoracoids ossified. Tips of fingers and toes not dilated.
Sternum very large. Madagascar .......... _Dyscophus._
Sternum small. Burmah .......... _Calluella._
_b_. Precoracoids not ossified. Tips dilated ..........
_Plethodontohyla._
_B_. Pupil horizontal.
_a_. Palatine teeth in long transverse series.
α. Precoracoids ossified. Tips dilated.
Fingers and toes free. Precoracoids entirely ossified ..........
_Mantipus._
Fingers and toes webbed at the base. Precoracoids semi-ossified
.......... _Platyhyla._
β. Precoracoids not ossified. Tips not dilated ..........
_Phrynocara._
_b_. Palatine teeth in one or two small groups.
Precoracoids ossified. Tips dilated.
Two small groups of palatine teeth .......... _Platypelis._
One single group in the middle of the palate .......... _Cophyla._
No teeth on the palate .......... _Anodontohyla._
_Dyscophus antongili._–Madagascar. General appearance stout, with short
legs and a wide mouth. Total length about 3 inches. The skin is mostly
smooth, and forms a broad glandular fold which extends from the eye to the
groin. The upper parts are beautiful magenta red, with a purplish streak
beneath the lateral folds; the under parts are yellowish white, with minute
grey specks. Red or pink colours, and the lateral folds, occur also in most
of the other members of this family, for instance in the Indian genus
_Calluella_.
SUB-FAM. 3. GENYOPHRYNINAE.–_With very small teeth on the anterior portion
of the lower jaw._
_Genyophryne thomsoni._–Pupil horizontal. Tongue oblong and entire. With
teeth on the palatine bones, and a serrated transverse dermal ridge in
front of the oesophagus. Sternum cartilaginous. Precoracoids absent. Sacral
diapophyses moderately {237}dilated. Tympanum hidden. Head large and much
depressed. Heel with a triangular dermal flap. The smooth skin is pink
brown above, with blackish marks; a light line extends on each side from
the eye along the back. Under parts black. About 32 mm. in length. Sudest
Island, between New Guinea and the Louisiade Archipelago.
FAM. 7. RANIDAE.–Frogs, in the true sense, are all well diagnosed as
_Firmisternia, with cylindrical sacral diapophyses_. According to the
presence or absence of teeth in the jaws they can be subdivided as
follows:–
SUB-FAM. 1. CERATOBATRACHINAE, with teeth in the upper and in the lower
jaws. The sole representative is the genus _Ceratobatrachus_.
SUB-FAM. 2. RANINAE, with teeth in the upper, but none in the lower jaw.
These are the Ranidae of Boulenger in the Catalogue of Batrachia Salientia.
SUB-FAM. 3. DENDROBATINAE, without teeth in the upper and lower jaws.
SUB-FAM. 1. CERATOBATRACHINAE.–Teeth present in both jaws. Those of the
lower jaw, between 20 and 30 in number in _Ceratobatrachus_, the only
genus, are nearly all inserted upon the articular bone; only 2 or 3 are
carried by the dentary element, which, although large, enters into the
formation of the upper border of the jaw at the anterior end only. In the
small extent of the share of the dentary in the formation of the edge of
the lower jaw, and in its anterior "toothlike" process, _Rana adspersa_ of
Africa bears unmistakable resemblance to this genus. The tongue is deeply
notched, and free behind. Pupil horizontal. Vomers furnished with teeth.
Tympanum distinct and large. Precoracoids present. Omosternum and
presternum with a bony style. Sacral diapophyses cylindrical. Fingers and
toes free, with swollen tips. Outer metatarsals united. Male with two
internal vocal sacs.
_G. guentheri_, Solomon Islands, the only species, has an enormous mouth
and a triangular head not much smaller than the rest of the body. The skull
is furnished with prominent ridges and a small curved spine at the angle of
the jaws. The hind-limbs are rather short. The skin of the upper parts
shows linear ridges, variously arranged; that of the belly is granular. A
triangular dermal flap on the tip of the muzzle, one on the {238}upper edge
of the eyelids, others on the heel and above the vent. The colour and
markings are very variable, the ground-colour is yellowish to pink, brown,
grey or olive, with darker and lighter markings. Total length of the males
3 inches, of females 3½ inches.–Guppy, the discoverer of this peculiar
creature, remarks that "horned Frogs are very numerous in these islands,
and so closely do they imitate their surroundings in colour and pattern,
that on one occasion I captured one by accidentally placing my hand on it
when clasping a tree."
SUB-FAM. 2. RANINAE.–The vertebrae are procoelous and devoid of ribs. The
precoracoids are always present and ossified from the clavicles, and are
parallel with the much stronger and ossified coracoids. The omosternum
usually possesses a bony style, but in the Indian genera _Nannobatrachus_
and _Nannophrys_ and in _Phyllodromus_ of Ecuador it remains cartilaginous,
and in _Colosthetus_ of Colombia it is absent. The metasternum also
possesses a bony style, but it remains cartilaginous in the Indian genera
_Oxyglossus_, _Nannophrys_, _Nannobatrachus_ and _Phyllodromus_, in the
last two genera rather reduced and slender, while in the Ecuadorian and
Colombian genera _Hylixalus_, _Prostherapis_ and _Colosthetus_, it is
reduced to a membranous piece. In quite a number of genera the normal
number of phalanges is increased by one owing to the intercalation of an
extra phalanx between the terminal and the otherwise penultimate
phalanx.[104] This is the case in all the species of _Cassina_,
_Hylambates_, _Rappia_, _Megalixalus_, _Rhacophorus_, _Chiromantis_,
_Ixalus_ and _Nyctixalus_, but it is doubtful if all these genera are
thereby more nearly related to each other than to the rest of the Raninae.
The structure of the tips of the fingers and toes exhibits more variety.
The terminal phalanges are mostly simple, with slight swellings at the
ends, or they are Y- or T-shaped in conformity with more or less developed
adhesive discs; in the African genus _Hylambates_ only they are
claw-shaped, as in the Hylidae.
_Gampsosteonyx batesi_, recently described by Boulenger from the Gaboon,
shows a unique modification of the terminal phalanges of the second to the
fifth toes. They are transformed into sharp and curved claws, like those of
a cat, but instead {239}of horny sheaths, it is the bone itself which is
thus sharpened and perforates the skin, an anomaly reminding us of the ribs
of _Triton waltli_. Total length of the type-specimens, about 3 inches.
Adhesive discs are common, and are best developed in _Rhacophorus_,
_Ixalus_, _Rappia_, and _Megalixalus_. In the Neotropical genera, excepting
_Colosthetus_, the discs are very peculiar, being provided on the upper
side with leathery scales which are separated by a fissure. The fourth and
fifth metatarsals either diverge and are connected by a distinct web, or
they lie close together with only a groove between them, or lastly they
appear externally united.
[Illustration: FIG. 46.–Map showing distribution of the Ranidae.]
The tympanic disc is very variable, large, small or quite hidden. Vomerine
teeth are present or absent. The pupil contracts into a horizontal slit
except in some Palaeotropical genera. The tongue is universally free
behind, mostly deeply notched, and can be well protruded; only in the
Indian _Oxyglossus_ and in the Neotropical genera, excepting _Hylixalus_,
its posterior margin is entire.–There are terrestrial, arboreal, and
aquatic members in this large sub-family. The geographical distribution of
the Raninae, which comprise about twenty genera with at least some 270
species, is almost entirely Arctogaean. None, with the exception of three
species in the Papuan subregion, occur in the Australian region; and only
four genera, with one or two species each, inhabit the tropical Andesian
district, the {240}remainder of South America being without any Raninae.
All the species of the whole Periarctic region belong to the genus _Rana_
except in Eastern Asia, where the closely allied genus _Rhacophorus_ occurs
also. The entire sub-family of Raninae is, in its fulness and diversity of
development, essentially Palaeotropical.
Many of the genera, even in the present more liberal sense as interpreted
by Boulenger, are based upon unimportant characters, and in reality run
into each other. This is for instance the case with _Rana_ and
_Rhacophorus_.
The following tabular arrangement is merely a key for determination and
does not necessarily express relationships. The presence or absence of
vomerine teeth is a character easily ascertained, but it separates closely
allied genera, for instance, _Rhacophorus_ from _Ixalus_ and _Micrixalus_
from Rana.
The genera with extra, interpolated phalanges are marked *.
KEY FOR THE DETERMINATION OF THE GENERA OF RANINAE.
I. Pupil vertical.
_A_. With vomerine teeth.
_a_. Omosternum very slender and cartilaginous. Small discs. India
and Ceylon, 3 species .......... _Nannobatrachus._
_b_. Omosternum with a bony style.
α. Outer metatarsals webbed. Small discs. South India, 2 species
.......... _Nyctibatrachus._
β. Outer metatarsals close together. Africa.
Fingers and toes with interpolated phalanges.
Without terminal discs. 2 species .......... _Cassina._*
With discs supported by claw-shaped phalanges, 10 species
.......... _Hylambates._*
Fingers and toes without interpolated phalanges; without discs.
Toes webbed .......... _Trichobatrachus robustus_,
p. 271.
Toes free, with sharp claws .......... _Gampsosteonyx batesi_,
p. 272.
_B_. Without vomerine teeth. Discs well developed. Outer
metatarsals united. Tropical Africa and Madagascar, 7 species
.......... _Megalixalus._*
{241}II. Pupil horizontal.
_A_. With vomerine teeth.
_a_. Outer metatarsals webbed together.
Fingers free, toes webbed .......... _Rana_, p. 249.
Fingers and toes more or less webbed. Always with discs ..........
_Rhacophorus_,* p. 245.
Two fingers opposed to the others. Africa ..........
_Chiromantis_,* p. 244.
_b_. Outer metatarsals united, or separated by a groove only.
Omo- and meta-sternum with a bony style .......... _Cornufer_,
p. 243.
Omo- and meta-sternum slender and cartilaginous.
Ceylon, 2 species .......... _Nannophrys._
Mozambique .......... _Phrynopsis boulengeri._
_B_. Without vomerine teeth.
_a_. Palaeotropical.
α. Tongue narrow and entire. No discs. Outer metatarsals webbed.
India, 3 species .......... _Oxyglossus_.
β. Tongue oval, feebly nicked. Large discs. Solomon Islands
.......... _Batrachylodes vertebralis._
Karin Hills .......... _Phrynoderma asperum._
γ. Tongue deeply notched. Outer metatarsals united by a web.
Discs none or very small.
Africa, 3 species .......... _Phrynobatrachus._
Borneo .......... _Oreobatrachus baluensis._
With regular discs.
Number of phalanges normal. India, 5 species ..........
_Micrixalus._
With an extra, interpolated phalanx. India, 18 species
.......... _Ixalus._*
Two fingers opposed to the others. Karin Hills ..........
_Chirixalus doriae._*
δ. Tongue heart-shaped. Outer metatarsals united.
Fingers and toes free, tips blunt. Africa, 8 species ..........
_Arthroleptis_, p. 242.
Fingers and toes more or less webbed, with regular discs. Africa
and Madagascar, 23 species .......... _Rappia._*
{242}_b_. Neotropical. Metasternum small, cartilaginous or
membranous. With discs.
1. With a pair of dermal scales on the discs. Omosternum with a
bony style.
Tongue heart-shaped. Ecuador, 2 species .......... _Hylixalus._
Toes free. 5 species .......... _Phyllobates_, p. 242.
Tongue entire. Ecuador and Colombia, 3 species ..........
_Prostherapis._
Omosternum cartilaginous. Ecuador .......... _Phyllodromus
pulchellus._
2. Discs without scales. Omosternum absent. Colombia ..........
_Colosthetus latinasus._
_Phyllobates._[105]–This is one of the few Neotropical genera, and like
nearly all of these has peculiar adhesive discs on the fingers and toes,
each disc bearing on its upper surface two dermal scales. The tympanum is
distinct. Vomerine teeth are absent. The general appearance of the five
species is that of tree-frogs. One species, _Ph. bicolor_, yellowish above,
dark brown beneath, lives in Cuba. The others inhabit Central America and
Venezuela. They seem to have peculiar nursing habits. _Ph. trinitatis_ of
Venezuela and Trinidad carries its tadpoles on its back, on to which the
young fix themselves by means of their suckers. Nothing is known about
their breeding habits, for instance whether the young are hatched on the
back, or, as seems more likely, if the parents (the specimen described by
Boulenger[106] is a male) only give their offspring a temporary lift in
order to convey them from a drying-up pool to a healthier place. It is
remarkable that several species of Dendrobatinae, which inhabit the same
countries, have precisely the same habits.[107]
_Arthroleptis._–Slender and long-limbed little frogs, about one inch in
length. The fingers and toes are free, very slender, and end in slightly
dilated tips, the supporting phalanges being simple. The tympanum is
variable. The skin is smooth or finely granulated. The colours are
inconspicuous, brown or grey tones usually prevailing. About ten species
are known, mostly {243}from Continental Africa, a few from Madagascar and
the islands in the Indian Ocean.
_A. seychellensis._–Brauer[108] has discovered the mode of nursing of this
frog. He found a specimen of _A. seychellensis_ which carried nine tadpoles
on its back, in the month of August, in the Seychelles, about 1500 feet
above sea-level, upon an old tree-fern. The little ones were already
provided with long tails, the hind-limbs were partly free, the fore-limbs
still covered by the skin, and they held on by their bellies; not, like the
young of _Phyllobates_, by their "suckers." Another specimen carried young
which were still further developed. He also found an old frog, near which
was lying a little heap of eggs, not enveloped in a common mass of jelly.
The old frog escaped, but the eggs were taken care of in a vessel with
moist sand at the bottom. By the following morning the eggs were hatched
and the tadpoles were clinging by their bellies on to the walls of the
glass. Brauer concludes that the young, when hatched, creep on to the
parent's back, he or she waiting near the heap of eggs until the latter are
ready. Curiously enough, he did not find out the sex of the nurse, nor are
we told if the young are taken to the nearest water to finish their
metamorphosis, or if they remain upon the parent's back until they hop off
as baby-frogs. The yolk is very large. When the four limbs are already
developed, the gill-cavity possesses no gills and no outer opening; and
since the lungs are only just beginning to sprout, the tadpole must needs
breathe by means of its skin. The jaws have no horny coverings. The adults
live on the ground between moist leaves, and eat chiefly termites.
[Illustration: FIG. 47.–_Arthroleptis seychellensis_, carrying Tadpoles. ×
1. (After Brauer.)]
_Cornufer_, with about twelve species, is an essentially Austro-Malayan and
Polynesian genus, but one species, _C. johnstoni_, has been found in the
Cameroons. The fingers and toes are free, and their T-shaped phalanges
support adhesive discs. The tympanum is distinct. The general shape is
frog-like, usually with slender and very long hind-limbs and toes, the
discs of the latter being much smaller than those of the fingers. The
coloration is dull, mostly brown, more or less marbled, whitish below. The
{244}upper eyelid of some species, _e.g._ of _G. unicolor_ of New Guinea,
has a small tubercle, hence the generic name. The skin of the back is
glandular and granular, forming slight folds on the back and on the sides
of the head in some species. The male has one or two internal vocal sacs.
_C. corrugatus_ is one of the most widely distributed species, inhabiting
the Philippines, New Guinea, and Duke of York Island. The granular skin
forms longitudinal folds on the back, one of which reaches from the eye to
the shoulder. Brownish above with darker markings, below yellowish, with or
without brown spots on the throat.–Three species inhabit the Fiji Islands.
Of _C. solomonis_ of the Solomon Islands little is known about the
propagation, although the large size of the egg, which measures 5 mm. in
diameter, suggests that the young undergo most or the whole of their
metamorphosis within the egg.
_Chiromantis_ is distinguished by the peculiar arrangement of the fingers,
the first and second being opposed to the others; their terminal phalanges
are obtuse and support small knobs or discs. The general shape is that of a
frog with long and slender hind-limbs. The tympanum is distinct.
_Ch. xerampelina_, the type-species, was discovered by Peters at
Mozambique; it is a middle-sized frog, about 2 inches in length, brown
above with reddish spots on the sides; the male is devoid of vocal sacs.
_Ch. petersi_, a native of East Africa, differs from the preceding by the
possession of an internal vocal sac. _Ch. rufescens_ = _guineensis_ shows
very little of the typical grasping arrangement of the fingers; the two
inner ones are separated from the two outer fingers by a wide gap, but they
all lie in the same plane, are much webbed and possess large discs, so that
by the latter two characters a link is formed with _Rhacophorus_, to which
the present genus is closely allied. Total length about 2½ inches.
Buchholz[109] has observed the peculiar breeding habits of this rather
large, brown, and slender tree-frog in the Cameroons. In the month of June
he found on the leaves of a low tree, standing in the water, a white foamy
mass, like the froth of a broken egg, containing a number of newly hatched
larvae and quite transparent eggs. Within three or four days this mass
became {245}fluid, and the larvae, provided with external gills and a long
tail, swam about in the slime. In the natural course of events the larvae
are probably washed down into the water by the rain. He found that the
female deposits the eggs in the foamy mass at night, during the months of
June and July, on various kinds of trees, either between the roots or in a
cavity formed by gluing together several leaves, sometimes 10 feet and more
above the water, or near the margin. On one occasion the mother was seen
sitting upon the foamy mass, clasping the same with its four limbs.
_Rhacophorus._–This large genus, containing more than forty species, has a
curious distribution. At least one dozen species are found in Madagascar,
eight or nine in Ceylon, the rest in Southern India, the Himalayas, the
Malay Islands and Philippines, extending northwards through China and
Southern Japan. Therefore this genus, with the three species of the African
_Chiromantis_, extends over the whole of the Palaeotropical region. The
generic name has reference to the possession by many species of little
dermal flaps, especially at the inner side of the heel, and it has nothing
to do with the parachute-like use of the hands and feet of certain species,
to be mentioned presently.
The terminal phalanges are generally bifurcated, rarely obtuse, and support
well-developed adhesive discs. The fingers and toes are webbed to a
variable extent. The two outer metatarsals are likewise connected by a web.
The tympanum is distinct. The general appearance is that of tree-frogs, and
many of them are green. The males have one or two internal vocal sacs. Not
all the species have dermal appendages. _Rh. maximus_, for instance, the
largest of all, living in the Himalayan forests, has none. A heel-flap
occurs in some half-dozen Indian species; and _Rh. madagascariensis_ has
these flaps on the heels and on the elbows. Some have queer little lappets
above the vent, or on the edges of the arms and legs; in others the bend of
the arm is fringed. The small size of these appendages, in comparison with
the webs and discs, makes them practically useless so far as increase of
surface is concerned, and they have most likely some other, although
unknown meaning, especially the flaps over the vent. Lastly, in the
majority of species the fingers are not more than half-webbed, or even
less, and in a few only, the webs reach down to the discs.
{246}Several species of this genus are remarkable for two reasons. First,
the great enlargement of the fully-webbed hands and feet, which are then
used as parachutes; secondly, the mode of propagation.
Greatly exaggerated notions are, however, entertained about the parachutes,
ever since Wallace's description[110] of the first "flying frog." The
creature was brought to him in Borneo by a Chinese workman. "He assured me
that he had seen it come down, in a slanting direction, from a high tree,
as if it flew.... The body was about four inches long, while the webs of
each hind-foot, when fully expanded, covered a surface of four square
inches, and the webs of all the feet together about twelve square inches."
[Illustration: FIG. 48.–_Rhacophorus pardalis_, × about 1. (From Wallace,
_Malay Archipelago_.)]
The species in question is _Rh. pardalis_, an inhabitant of Borneo and of
the Philippine Islands. Specimens from Wallace's Collection are in the
National Collection and the largest specimen {247}shows the following
measurements. Total length 6.5 cm. or 2½ inches, not 4 inches.
Area covered by one fully-expanded hand 3.4 square cm.
" " " foot 6.0 " "
–––
9.4 square cm.
_i.e._ for the four limbs 18.8 square cm. = about 3 square inches, and not
78 square cm. or 12 square inches. By some unfortunate oversight Wallace
must have mixed up the total expanded area with that of the four hands and
feet! In Brehm's _Thierleben_ the 78 square cm. have increased to 81 cm.,
and the artist has in the somewhat larger species _Rh. reinwardti_ improved
upon this, and has produced a truly startling picture by a further
exaggeration based upon the figure given by Wallace.
_Rh. reinwardti_ lives in the forests of the mountains of Java and Sumatra.
It reaches 3 inches in length, and is grass-green above, yellow below.
Younger specimens are further adorned with large blue patches on the webs
of the hands and feet and behind the armpits. Besides the flap on the heel
and the curious cutaneous fringe on the forearm, suggestive of an incipient
flying-membrane, the skin forms a projecting fringe on the inner side of
the fifth toe and a transverse flap above the vent.
Of _Rh. leucomystax_, Annandale, who accompanied the Skeat Expedition to
Malacca, gives the following account:–"This frog, which is called by the
Malays of Lower Siam either 'Berkata Pisang' (banana-frog) or 'Berkata
Rhumah' (house-frog), lays its eggs either on leaves of branches
overhanging the water, or on the mud surrounding buffalo-wallows. The ova
are enclosed in a round mass of yellow froth, which afterwards becomes
steel-grey, about as large as a cricket-ball. Should they be placed
judiciously in a position sheltered from the sun, the tadpoles may either
hatch, and reach a considerable degree of development, before the mass is
washed into the water, or the froth may be melted almost as soon as it is
formed and the eggs be carried into a pool by a shower of rain. Very often,
however, the whole mass is dried up by the heat of the sun before the rain
comes. During the breeding season, which seems to occur as often as the
land is flooded under the trees, for I have never seen the eggs of this
frog on the bank of a river, the {248}males croak loudly, producing a sound
which can hardly be distinguished from the chattering of the large black
and yellow squirrel, _Sciurus bicolor_."
These arboreal frogs have a peculiar mode of nursing the young and taking
care of the eggs. _Rh. maculatus_ of Ceylon, Malacca, etc., and _Rh.
schlegeli_ of Japan, lay their eggs in a foamy mass, the size of a fist, on
the margins of ponds, and the whole process has recently been described by
Ikeda.[111] He observed the Japanese _Rh. schlegeli_ depositing the eggs in
soft, muddy ground covered with grass, and in wet, muddy banks of
paddy-fields, ponds, and similar localities near Tokyo. Sometimes they are
deposited between the leaves of trees, near the ground. The breeding season
extends from the middle of April to the middle of May. Towards the evening
the female, bearing the much smaller male on her back, retires underground
for the deposition of the eggs. The spots chosen are 10-15 cm. above the
surface of the water; the female digs a spherical hole 6-9 cm. wide.
Sitting thus concealed underground, the frogs assume a dark colour and the
spawning takes place during the night, whereupon the parents leave the
nest. The eggs are enveloped in a white mass of jelly full of air-bubbles,
the whole frothy lump looking like the well-beaten white of a hen's egg,
with the yellowish eggs scattered through it, and measuring some 6 cm. in
diameter. The air-bubbles are 2-3 mm. large. The froth is originally very
elastic and sticky, but it gradually sinks down, becomes liquid and
ultimately runs out of the hole. It is produced in the following peculiar
manner. During and after the deposition of the eggs the female puts her
feet upon the sticky jelly, part of which adheres and is then pulled out as
a thin, transparent membrane stretching between both feet. The latter are
then thrust backwards, the membrane is folded downwards and becomes a
vesicle of 5 to 10 mm. in width. By repeated working of the limbs the
successively formed bubbles are trodden and kneaded into froth, which
ultimately surrounds and at the same time separates the eggs.
The female of _Rh. reticulatus_ of Ceylon attaches the eggs, about twenty
in number, to the under surface of her belly, on the skin of which they
leave little cellular impressions. What becomes of the tadpoles is not
known.
{249}_Rh. leucomystax_ is found in the Malay Archipelago, Farther India,
and the Philippine Islands.
S. S. Flower[112] found the tadpoles about Singapore, from January to
April, in small ponds and in rain-water butts. The spiracle lies on the
left side, directed backwards and upwards, nearer the anus than the end of
the snout. The anus opens on the right side. Exceptionally large tadpoles
measured 46 mm. in total length, the recently transformed young only 14-18
mm.
"A cheerful little frog of most graceful build. It comes out from its
hiding-places shortly before sunset, and remains abroad all night. The
males are easily found as they sit on shrubs or trees, or on the edges of
the rain-water butts under the verandahs of the houses, and from time to
time utter a single, rather musical, short croak. In March and April they
can be found both by day and night in embrace, in the ponds. This species
changes both its colour and markings very rapidly and frequently, but dark
bands across the legs can always be more or less distinguished; the lower
parts are some shade or other of buff, but the principal variations of the
upper part are as follows: pale bronze, either uniform or with four
longitudinal dark-brown or black lines; uniform, almost orange, bright
bronze; chocolate, with darker mottling; pale brownish green or olive, with
irregular dark spots; yellowish green, mottled with darker or brown." The
females are considerably larger than the males; the largest male caught was
48 mm. from snout to vent, and the largest female 68 mm.
_Rana._–The following combination of characters should be a sufficient
diagnosis: pupil horizontal; tongue deeply notched and free behind; vomers
with teeth; fingers free, toes webbed, fourth and fifth metatarsals
diverging and webbed together.
In conformity with the great number of species and the wide distribution of
this genus some of the organs vary considerably, indeed so much so that
many of these modifications have been deemed sufficient to be of generic
importance. Fortunately the species are so numerous that these characters
mostly form an uninterrupted series from one extreme to the other.
The terminal phalanges are mostly simple and pointed; sometimes
transversely dilated or T-shaped, according to the presence of more or less
developed discs. Such discs are, for {250}instance, present in the Malay
species _R. erythraea_ and _R. chalconota_ and in the Indian _R.
corrugata_. The tympanum occurs in every stage from a conspicuous, free
disc to being quite hidden by the skin. The vomerine teeth either form a
pair of tiny, mostly transverse rows, between the choanae, or they are
arranged in two oblique series which extend beyond the hinder edges of the
choanae.
The vocal sacs vary greatly. Many species, e.g. _R. agilis_, have none at
all. Most species have a pair of internal sacs, and in comparatively few,
about a dozen, these sacs have become external, a feature which indicates
no relationship of the species thus distinguished, for instance the
European _R. esculenta_, the Japanese _R. rugosa_, the Indian _R.
hexadactyla_, _R. cyanophlyctis_ and _R. Chloronota_, the Bornean _R.
glandulosa_, the African _R. oxyrhynchus_ and _R. mascareniensis_, the
Mexican _R. montezumae_. In _R. esculenta_, and perhaps in a few others,
even the female has some traces of these otherwise male organs, indicated
by slit-like folds of the outer skin below the angles of the lower jaw.
Nuptial excrescences on the inner metacarpal tubercle and on the inner
fingers of the male are common; they reach their greatest development in
the Himalayan _R. liebigi_, the male of which is "remarkable for the
extreme thickness of its arms, the inner sides of which are studded with
small conical black spines, each supported on a rounded base produced by a
swelling of the skin. A large patch of similar spines exists on each side
of the breast."[113]
Specific glandular complexes in the skin are mostly restricted to a pair of
lateral or dorso-lateral folds; they are often absent, but a few species,
e.g. _R. glandulosa_ of Borneo, _R. temporalis_ of Ceylon, _R. elegans_ and
_R. albolabris_ of West Africa, have a pair of large flat glands at the
base or inner side of the arms.
All the species of _Rana_, except those in the Solomon Islands, spawn in
the water, where the development of the tadpoles takes its course. Those of
some Indian species, notably _R. alticola_ and _R. afghana_ of the
Himalayas, and _R. curtipes_ of Malabar, are very peculiar, being provided
on either side of the shoulders with a large oval parotoid-like gland, well
defined and crowded with pores; _R. alticola_ possesses in addition an
unpaired, sharply {251}marked glandular complex on the top of the root of
the tail, or rather upon the future coccyx. These complexes gradually
disappear with age.
The genus _Rana_, with about 140 species and subspecies, is distributed
over the whole of Arctogaea so far as this is available for Amphibian life,
while there are only a few stragglers in Notogaea, namely, a few species in
Ecuador and in the Peruvian or Upper Amazon district. None exist in the
rest of the Neotropical region, including the Antilles, and practically
none in Australia; but _R. arfaki_ and _R. papua_ inhabit New Guinea and
the northern corner of Australia, _R. kreffti_ the Solomon Islands. A few
species are restricted to Madagascar, and a few others live there and on
the continent of Africa.
So far as number of species is concerned, the home of the genus _Rana_ is
the Palaeotropical region; about one dozen (some of them with a very wide
range) live in the Palaearctic sub-region, scarcely more in the Nearctic
sub-region, and a few in Central America.
_R. temporaria_ (the common European Brown Frog or Grass-frog).–The
tympanum is distinct, two-thirds the diameter of the eye in size. The first
finger is slightly longer than the second, which is shorter and weaker than
the others, whilst the fourth is the longest. All the fingers are quite
free. When the hind-limbs are laid forwards along the body, the ankle-joint
reaches to a point between the eye and the tip of the snout. The five toes,
which are about half webbed, increase in length from the first to the
fourth, while the fifth is about equal to the third. The sole of the foot
has a small, blunt, inner metatarsal tubercle; the outer one is scarcely
visible. The skin is smooth, always moist, owing to the minute mucous
glands; but a series of larger glands forms a pair of folds along the upper
sides of the back; beginning behind the eyes they converge slightly beyond
the shoulders, diverge a little in the sacral region, and converge again
towards the vent. Another, much feebler, Λ-shaped ridge lies between the
shoulders.
The male has two internal vocal sacs, which, when in use, bulge out the
skin of the throat beneath the angles of the mouth like a pair of globes.
It is further distinguished from the female by the stronger muscles of the
arms and by a pair of swollen pads on the inner side of the first finger.
During the pairing {252}season these pads are enlarged into cushions
covered with black horny rugosities.
The iris is golden, with dark specks. The coloration is, generally
speaking, brown above, with black-brown irregular spots, especially on the
sides of the body, and with cross-bands on the legs. The under parts of the
male are white or pale yellow, with a bluish tinge on the throat, while the
female is more yellow instead of white, inclining to orange. In both sexes
the under parts are mostly spotted with darker colours. A large dark-brown
patch, extending from behind the eye over the tympanum towards the
shoulder, is always present and has given this frog its specific name.
Otherwise the coloration varies considerably; more or less according to the
locality and nature of the surroundings, and to individual variation and
temporary change of colour.
Some specimens are almost spotless above and of a rich brown, or almost
yellow colour, the spots being restricted to the sides below the lateral
folds. Others have very few spots, but these are then arranged in two
interrupted streaks on the back. The under parts, especially the flanks,
may be lemon yellow instead of whitish, and the darker markings may be
almost absent. Boulenger has figured a beautiful specimen, almost orange
red, with red spots and vermiculations on the yellow under surface. I have
found similar red specimens of unusually striking appearance between Berlin
and Spandau in a forest-glade, through which run little streams with banks
of red ferruginous soil. Specimens which live in woods with rich black soil
are often very dark, all the brown and reddish tints being absent. The
variations are, however, really endless, and it is difficult to find two
individuals exactly alike, even amongst a great number collected in the
same locality. Moreover, they change colour. Warmth makes them paler, cold
causes the chromatophores to expand and the whole frog appears darker.
During the breeding season the males assume a delicate bluish hue,
especially on the throat, but this film quickly fades away when they are
taken out of the water. It is caused by the swelling of the cutaneous
lymph-spaces which extend their ramifications into the epidermal layer, and
it is not a question of pigmentation or of chromatophores, but a case of
interference-colours, blue being frequently the result of the light passing
through a cloudy, colourless, but not {253}quite transparent and thin
stratum, in this case the turgid epidermis.
The habits of the Grass-frog are essentially terrestrial. It spends most of
its time on land, preferably in damp places, but local fashion permits of a
great deal of freedom, as these frogs are sometimes found not only in very
wet, naturally irrigated places, but also in the water itself. However, the
Grass-frog when pursued rarely takes to the water for safety. It trusts to
flight, first by a few long and fast jumps, and then to concealment by
squatting down between grass, under leaves; it rarely creeps into a hole,
even if there be one near. The jumps soon become shorter and shorter after
a few dozen repetitions. It swims well, but cannot climb. The food, which
consists chiefly of insects, snails, and worms, must be moving to excite
interest; then the frog, whose favourite position is half squatting, half
supported by the arms, erects itself, and, facing the insect, turns round
upon its haunches, adjusts its position anew by a shifting of the legs, and
betrays its mental agitation by a few rapid movements of the throat. All
this time the prey is watched intently until it moves; then there follows a
jump, a flap of the tongue and the insect is seen no more. As a rule these
frogs do not crawl, they jump or hop, even whilst stalking, and this takes
place at any time of the day; in fact they are very diurnal, although they
become more active towards the evening. When caught they are at first very
wild and, like all true frogs, very impetuous, committing acts of
astonishing stupidity without any apparent sense or appreciation of
distance or height. The captive will not only jump off the table, whilst a
toad stops at the edge and looks carefully down, but without hesitation he
jumps out of the window, regardless of the height above the ground. This is
due to sheer fright; he loses his head. When at large in his native
surroundings, nothing will induce him, although hotly pursued, to commit
suicide by jumping down a precipice. But all this wildness calms down
wonderfully soon. The captive no longer dashes his head against the glass,
he does not struggle or twist when taken up; on the contrary, he makes
himself at home, watches your coming with intense expectation, and without
hesitation accepts the proffered mealworm, maggot, butterfly or earthworm;
in short, he shows what a jolly and intelligent fellow he really is.
{254}The Grass-frog has many more obvious enemies than perhaps any other
Amphibian, and it is not even slightly protected by any appreciable
poisonous secretion. Nevertheless it is extremely common. A whole host of
birds eat it–for instance, buzzards, harriers, and above all storks. Foxes,
polecats, and stoats are not averse to it, and the Grass-snake derives its
main sustenance from it. In fact the enemies of the little frog are legion,
one of the worst being Man. In France, Italy, and other parts of the
Continent, the skinned fleshy hind-limbs are turned into a by no means
disagreeable ragoût, or into dainty morsels when fried in butter and
encrusted with bread-crumbs. This frog, together with its cousin the
Water-frog, also suffers from the distinction of being one of the chief
martyrs to science. Perhaps the story is true that Galvani was led to his
investigations into animal magnetism and electricity by observing that the
legs of a number of skinned frogs, strung up by his wife upon the bronze
railings of the balcony, jumped whenever the scissors, which cut off the
feet, touched the other metal. Frogs have suffered ever since. Easily
procured and of a convenient size, they are used in every biological
laboratory, and the young student is supposed to be initiated into the
mysteries of Vertebrate structure by the careful dissection and study of
this, the worst of all the so-called types. Next to Man there is no animal
which has been studied so minutely, and has had so many primers and
text-books written on it, as this frog. In spite of all this it is very
little understood, thanks to its rather aberrant and far from generalised
structure.
However, the frog, by reason of its fertility, holds its own. Early in the
year, sometimes while there is still ice and snow, the frogs leave their
hibernating places (mostly holes in the ground, under moss, or in the mud),
and they begin to pair in standing or slowly flowing, mostly shallow,
waters.
They are not always very careful in the selection of the spawning locality,
many of them lay their eggs in a ditch, or even in the shallowest puddle,
which is sure to dry up, and thus to cause the destruction of the whole
brood. This carelessness is all the more surprising when there are large
pools or lakes in the immediate vicinity, perhaps only one hundred yards to
the other side of the road. The Natterjack is, by the way, equally
careless, while other toads and the tree-frogs are very circumspect.
{255}[Illustration: FIG. 49.–_Rana temporaria._ Eight successive stages in
the development from the egg to the almost complete Frog, × 1.]
Both sexes can croak, and this sound is frequently produced under water;
but there are no regular concerts, although many collect in the same pond
or spring, which is perhaps the only suitable place for miles around. The
male puts its arms around the chest of the female, behind her arms, and the
embrace is so firm that nothing will induce him to loosen his hold. The
process becomes an involuntary reflex-action, a cramp which may last for
days, or even for weeks, if sudden cold weather sets in, until the female
is ready to expel the eggs, an act which is quick and soon over. The usual
time of spawning in Middle Europe is the month of March, earlier in warm,
later in cold seasons; in southern countries, February or even January, but
in Norway not until May. Although the males of this species are not more
numerous than the females, and therefore should be able to mate without
much trouble, their ardour is so great that they occasionally get hold not
only of the wrong kind of frogs, but of toads or even fishes, and, if taken
off by force, they fasten on to anything else, a log or on to your own
fingers. The eggs measure 2-3 mm. in diameter, are black with a whitish
spot on the lower pole, number from 1000 to 2000, and sink at first to the
bottom. Their gelatinous cover soon swells to a large globe more than 10
cm. in width, and the whole mass, as large as a man's head, floats on the
surface, often stained with mud and other impurities. During the cold
weather which often prevails in the spring, the dark brown larvae are slow
in their development; and provided with rather large branched external
gills and a well-developed tail, they wriggle about in the dissolving slime
for three or four weeks. Fischer Sigwart[114] has timed and measured them
as follows.–The eggs were laid on the 10th of {256}March. On the 15th the
larvae were 4 mm. long and began to leave the eggs. On the 19th they
measured, body 4, tail 9, total 13 mm.; on the 5th of April 10, 16, and 26
mm. respectively. On the 13th of May they were 40 mm. long and the
hind-limbs appeared; the fore-legs burst through on the 25th, when the
tadpoles had reached their greatest length, namely 45 mm., the body
measuring 15 mm. On the 31st of May they left the water, still provided
with a rather long tail of 20 mm., the total length being reduced to 35 mm.
The larvae of this set developed unusually fast, perhaps owing to
artificial conditions. The whole development is, however, mostly finished
in three months, so that the little stump-tailed baby-frogs swarm about
well before midsummer, and have time enough to grow to the size of 20 mm.
or ¾ inch before they begin to hibernate in October.
In higher localities and in northern countries the tadpoles are sometimes
obliged to winter in the unfinished condition.
In spite of the unusually hot summer of 1899 I found plenty of tadpoles on
the 10th of September in the tarns of the hills of North Wales, 1500 feet
above the level of the sea; while thousands of little frogs, with and
without stumpy tails, were hopping about in the surrounding bogs. The water
of these tarns is always very cool. Cold and rainy weather set in by the
middle of the month, and on the 26th the tadpoles, all rather small,
measuring only 35 mm., with the four limbs developed, but still with a
broad fin on the tail, had all settled down under stones at the bottom of
the now very cold water, prepared for hibernation. A few were taken home
and kept in a glass vessel with water, cool, but less so than that of their
native tarns. Within two days they lost the fins on their tails; before the
end of a week they left the water, and crawled on to the moss, and the
tails were reduced to little stumps. By the 10th of October the
metamorphosis was complete, the little frogs measured only 13 mm. in length
and showed no desire to hibernate in the genial atmosphere of the
greenhouse.
This species has a very wide distribution. It ranges from the west of
Ireland to the islands of Saghalin and Yezzo, being found everywhere in the
enormous stretch of intervening countries, practically the whole of Central
and Northern Europe and the middle belt of Asia. Its most northern extent
is the whole of Sweden and Norway. I have found it to the east of the
{257}Dovrefjeld, at an elevation of 4000 feet, well-nigh the snow-line. In
conformity herewith it ascends the Italian Alps up to 10,000 feet. The
southern limit in Europe is the Cantabrian range and the hilly province of
Galicia. In the rest of the peninsula, in Italy and Lombardy, Greece and
Turkey, and on the Mediterranean islands it is absent.
_R. arvalis_ is often confounded with _R. temporaria_, as it differs from
the latter only by the following characters. The snout is rather more
pointed and is narrower; the inner metatarsal tubercle is large,
compressed, and hard; the dorso-lateral glandular folds are more prominent
and the belly is white and immaculate; lastly, it scarcely reaches 3 inches
in length, a size which is not rarely surpassed by the other species. There
are also some differences in habits. _R. arvalis_ prefers moist, boggy,
open localities, and does not ascend beyond 2000 feet in Central Europe. It
pairs as a rule later in the spring and the eggs are smaller, only 1½-2 mm.
in diameter; they do not swell up so much, and the whole mass does not
float but remains at the bottom of the shallow water. The coloration much
resembles that of _R. temporaria_, and is likewise subject to much
variation, except that the pale vertebral stripe is perhaps more common.
This species is distributed over the whole of Central Europe, Russia, and
Western Siberia, south of the 60th degree of latitude, living side by side
with _R. temporaria_. Between the rivers Elbe and Rhine it becomes
decidedly rare, and the latter river is practically its western boundary,
while the Bavarian Alps and the Danube form its southern limits.
_R. agilis_ is still more frequently confounded with both the two former
species. It differs from either by the absence of the two internal vocal
sacs of the male, and by the decidedly longer hind-limbs, the tibio-tarsal
joint reaching often a little beyond the tip of the snout. The inner
metatarsal tubercle is as prominent as in _R. arvalis_. Total length up to
3 inches. The prevailing colour of the upper parts is rather yellow or
pink-brown with few and small blackish spots; a Λ-shaped dark mark on the
neck is often present, and the large dark patch on the temporal regions is
always conspicuous. The under parts are white, inclining to lemon yellow on
the flanks and thighs. The iris is golden yellow in its upper half, dark
brown in the lower half.
{258}This species has a much smaller range than the first two:–from France
through Middle and Southern Germany, Switzerland, and Lombardy to Hungary
and Greece. The specific name refers to the quick and long leaps of this
pretty, or rather delicately coloured frog, which prefers woods and wooded
glens to large open places. Their voice differs much from the croak of the
common Brown Frog, and agrees with that of _R. arvalis_, which is
transcribed by Boulenger, who has kept them alive, as a rapidly uttered
"co-co-co," or "cor-cor-cor." According to the same authority, the pairing
takes place as in _R. temporaria_, but is of much shorter duration, the
females usually resorting to the water only at night and when quite ready
to spawn. Specimens in embrace are therefore seldom found in the daytime.
The eggs resemble those of _R. temporaria_ in size, but they do not swell
up so much and they do not float.
These three species of European brown frogs, difficult enough to
distinguish, have of late been increased by three more, thanks to the
sagacity of Boulenger. These latter inhabit South Europe, and the males all
lack the internal vocal sacs.
_R. iberica_ has a very small range, namely the north-western portion of
the Iberian peninsula, from the Tagus northwards into Galicia, but south of
the main extension of the Cantabrian chain. The rest of the Peninsula south
of these mountains has no brown frogs, the only species of _Rana_ being _R.
esculenta_. _R. iberica_ is rather local, being restricted to those hilly
and mountainous districts which are well watered. A favourite haunt is the
numerous streams in the wooded parts of the Serra Gerez, the red,
disintegrated granite of which suits this little, extremely active, and
reddish frog to perfection. The prevailing ground-colour varies according
to the district, from pale to dark reddish or orange brown, with red specks
and larger, dark brown spots, which in some specimens begin with the
Λ-shaped mark between the shoulders. Dark spots on the flanks are very
variable; the hind-limbs show the usual darker cross-bars, and the temporal
region has the conspicuous dark patch. The ground-colour of the under parts
is whitish, suffused with a pink tinge, and the throat is much speckled
with brown; the toes are pink. The size of this pretty frog amounts to 2
inches. The breeding time is the month of March. When caught and squeezed
they emit a slight "co-co-co."
{259}_R. graeca_ inhabits Italy and the Balkan peninsula from Rosina to
Morea, together with _R. agilis_, from which it is very difficult to
distinguish except that it is a little smaller, remaining below 2½ inches,
and is generally more uniformly pale grey brown to yellowish and pinkish
brown above, with scarcely any, or only a few, small dark specks on the
back and limbs. The temporal patch is likewise paler than in the other
species. The flanks are spotless, their colour gradually passing into the
light buff of the under parts, which are more or less marbled with grey.
The iris is golden, speckled with dark brown.
_R. latastei_ of Lombardy and Northern Italy down to Florence is the last
of these closely allied frogs. Its affinities lie with _R. iberica_ and _R.
agilis_. The latter and _R. latastei_, although living side by side in the
same locality, for instance near Turin, are said not to interbreed. The
voice is a rapidly uttered "keck-keck-keck;" the length remains below 2½
inches. The ground colour is greyish or reddish brown with a dark brown
Λ-shaped mark between the shoulders, and a few red, orange, or blackish
spots on the back. The flanks are without definite dark spots. The under
parts are whitish, with a strong pink tinge, especially along the middle of
the throat and on the chest, the paler portions being mottled with pale
grey brown.
Perhaps the least unsatisfactory way of distinguishing between _R. agilis_,
_R. graeca_, and _R. latastei_ (_R. iberica_ need not be confounded with
them on account of its distribution) is the size of the tympanum, and its
distance from the eye. The tympanum is smallest in _R. graeca_, its
diameter being about half that of the eye and from ¾ to the whole of its
width distant from the eye. In _R. latastei_ the tympanum is a little
larger, and about ½ to ⅔ its own width distant from the eye. _R. agilis_
has the largest tympanum, measuring about ¾ of the diameter of the eye, and
the distance between the two organs amounts to only ⅓ of the size of the
tympanum.
Brown land-frogs of the _R. temporaria_ group are found in most countries
of nearly the whole Periarctic and Oriental regions, and by the time their
races and varieties have been studied as minutely as those of Europe are
now being scrutinised, the number of species will indeed be great.
_R. silvatica_ is the chief representative in North America. It closely
resembles _R. agilis_, but is smaller, only 2 inches in length, {260}and
possesses a pair of internal vocal sacs. Its specific name refers to its
predilection for forests of oak, among the dried leaves of which it
conceals itself so successfully that it is discovered with difficulty. _R.
japonica_ of Eastern Asia is almost indistinguishable from this American
species and from the European _R. agilis_.
_R. opisthodon_ of the Solomon Islands has the vomerine teeth in two
oblique series entirely behind the level of the choanae. The general shape
of this large frog is stout, the type specimen of the male measuring 78,
that of the female 125 mm. = 5 inches. The upper surface of the female is
covered with small, flat warts, that of the male is much smoother. The
upper parts are dark brown, while the under surface is brownish white. The
male has two internal vocal sacs.
This species is interesting as affording another instance of shortened
development, the whole metamorphosis being gone through within the egg. Mr.
Guppy, its discoverer, has supplied the following notes: "During a descent
from one of the peaks of Faro Island I stopped at a stream some 400 feet
above the sea, where my native boys collected from the moist crevices of
the rocks close to the water a number of transparent gelatinous balls,
rather smaller than a marble. Each of these balls contained a young frog,
about 4 inches in length, apparently fully developed, with very long
hind-legs and short fore-legs, no tail, and bearing on the sides of the
body small tufts of what seemed to be branchiae. On my rupturing the ball
or egg in which the little animal was doubled up the tiny frog took a
marvellous leap into its existence, and disappeared before I could catch
it. On reaching the ship an hour after, I found that some of the eggs which
I had put in a tin had been ruptured on the way by the jolting, and the
liberated frogs were leaping about with great activity. On placing some of
them in an open-mouthed bottle, 8 inches long, I had to put the cover on,
as they kept leaping out."
Boulenger[115] has figured and further described the eggs and young. The
egg measures 6-10 mm. in diameter, and is a transparent capsule in which
the young frog is coiled up in the same way as figured by Peters in
_Hylodes martinicensis_; but none of the specimens, which are in an
advanced stage of development, show anything of a tail. There are no gills,
but on each side {261}of the abdomen are several regular transverse folds,
the function of which is probably that of breathing organs, like the tail
of _Hylodes_. The tip of the snout is furnished with a small conical
protuberance projecting slightly through the delicate envelope of the egg,
and evidently used to perforate that envelope.
_R. guppyi_, likewise an inhabitant of the Solomon Islands, is a giant
among frogs. It was discovered by Mr. Guppy on the Shortland Islands. The
type-specimen measures 165 mm. = 6½ inches in length! The skin of the upper
parts is covered with minute warts, and forms a strong fold above the
distinct, but small, tympanum. General colour dark olive brown above, dirty
white below.
_R. tigrina_ is a common species of Eastern Asia, including the Malay
Islands. On account of the strength of its voice, and its size, which is
said to reach 7 inches, it is called the "Indian Bullfrog." Mainly aquatic,
it has a strong cutaneous fringe along the outer side of the fifth toe. The
skin of the back is thrown into longitudinal folds, and a strong fold marks
the upper border of the tympanum. The general colour above is olive brown,
with dark spots, often with a light vertebral line; the under parts are
white. The male has a pair of large external vocal sacs.
_R. gracilis_ has the same distribution, but it remains much smaller, and
the toes are only half, instead of fully, webbed.
_R. catesbiana_ is now the settled name of _the_ "Bullfrog" of North
America, the much more appropriate name of _mugiens_ having been sacrificed
to the fetish of priority. The tympanum is extraordinarily large, at least
equal to the size of the eye, largest in the male. The first finger does
not extend beyond the second; the toes are connected by a broad web down to
the ends, and there is a small inner, but no outer, metatarsal tubercle.
The upper parts are olive brown, clouded with dark brown or blackish spots;
the under parts are yellowish white, often marbled with brown, especially
on the throat. The iris is reddish, with an outer yellow ring. The male
possesses two internal vocal sacs. Total length of adult specimens about 5
inches, but there are giants on record 7 inches in length, while the
stretched hind-limbs measure another 9 or 10 inches. Its home extends over
the whole of the United States, East of the {262}Rocky Mountains,
southwards into Mexico, northwards into Canada.
According to Holbrook the Bullfrogs are solitary in their habits, only
collecting together in the breeding season, when hundreds may be seen in
the same small pond; and then the croak uttered by the males is so loud as
to resemble the distant roaring of a bull, and can be heard on still
evenings at a distance of half a mile. The voice is a hoarse bass "brwoom,"
playfully translated into "more rum." "They cannot be said to abound, but
are found commonly enough sitting half immersed in water, or on the banks
of ponds, waiting for their prey. If alarmed they hop suddenly into the
water, but do not conceal themselves at once, frequently skimming along the
surface for several yards before they dive below." They are the most
aquatic of all the North American frogs, and Holbrook has known specimens
to live in wells for years, where they could not rest a moment on solid
ground above the water.
The Bullfrog is voracious, and takes almost anything that lives or gets
into his own pond–Mollusca, Crustacea, fishes and, above all, frogs. There
is no doubt that they drag down and swallow a good many ducklings and the
young of other water-fowl, but certainly not the half-grown birds which
have a way of disappearing from the farms wherever there are negroes and
other farm-hands about. In turn the bullfrog has sufficient enemies to keep
its numbers down, in fishes, birds, otters, and snakes, and, in the South,
alligators. Although easily kept and growing comparatively tame, they are
dull, having to be kept in solitary confinement on account of their
greediness, which knows no limits. Two of our specimens each swallowed a
full-grown _Salamandra maculosa_, and died within the same night, probably
not understanding the meaning of the conspicuous black and yellow warning
colours of the European.
_E. clamata_ s. _fontinalis_, likewise an inhabitant of Eastern North
America, may be called a smaller edition of the Bullfrog, its usual
full-grown size being about 3½ inches. The tympanum is conspicuously large,
but the toes are webbed to a lesser extent, and the skin forms a glandular
fold which extends from the shoulder in a curve to the flank. This species
is partial to the neighbourhood of running streams; it is said to be
{263}exceedingly timid, and to utter a short cry when disturbed and making
its enormous leaps.
Another North American relation is _R. halecina_ s. _palustris_,
frequenting the neighbourhood of ponds and rivers, very lively and capable
of jumping 8 to 10 feet. The tympanum is smaller than the eye, but there is
the same glandular lateral fold as in _R. clamata_. The vocal sacs are
internal and decidedly small.
[Illustration: FIG. 50.–_Rana clamata_, × ⅔.]
_R. esculenta._–The common Water-frog of nearly the whole Palaearctic
region is closely allied to the American Water-frogs described above, and,
like most of them, has the vomerine teeth in two small oblique rows between
the choanae and extending a little beyond their posterior border. But the
males have a pair of external vocal sacs. The tympanum is distinct, about
two-thirds the size of the eye. The first finger is slightly longer than
the second. The toes are entirely webbed. Besides the usual subarticular
phalangeal tubercles, the sole of the foot is provided with two metatarsal
tubercles, the outer of which is very small, while the inner is much
larger, although varying in size from a soft oval to a long, curved,
shovel-shaped structure. The skin is smooth, except for a pair of prominent
glandular folds which extend from behind the eye along the dorso-lateral
line. The coloration varies considerably. The upper parts are mostly
greenish brown, with black brown spots on the back, and larger patches on
the limbs. Most specimens have three lighter stripes along the back, the
middle one mostly green, the two lateral bronzy brown and coinciding with
the glandular folds. The tympanum is brown, and there is occasionally a
dark temporal patch. The posterior aspect of the thighs is invariably
{264}spotted with black and white or yellow, in opposition to the _R.
temporaria_ group, where these parts are never spotted.
The total length of this species varies much. Specimens 2½ inches in length
are certainly mature, those of 4 inches are unusually large, and Boulenger
has received a giant from Damascus, which measured 125 mm., or nearly 5
inches. The females are larger than the males.
The variations in colour are not only local but also individual, moreover
the colours are changeable. The ground-tint ranges from dull brown through
olive to bright green, the dark spots being more or less pronounced and
numerous; the light vertebral line is olive-yellowish, bright green, or
altogether absent.
Those which inhabit waters with plentiful vegetation, like water-lilies and
other luxuriant plants, are generally prettier and more vividly coloured
than those which live in swamps and ponds with dark mud, or where the
prevailing vegetation has a sombre aspect. Cold and dull, warm and sunny
days also influence the water-frogs, and those which have been kept in a
dark tank look very different from the bright assembly which had been put
in some weeks before.
Various attempts have been made at subdividing _R. esculenta_ of Linnaeus
into sub-species, and Boulenger has now, after the attentive study of an
enormous material, arranged them in four principal and recognisable races.
The chief differences are the relative length of the femur to the tibia and
the size of the metatarsal tubercles.
1. Var. _ridibunda_, Pallas.–The right and left heels overlap each other
when the thighs are stretched out at right angles to the vertebral column,
and the tibia is closely folded up against the thighs. When stretched
forwards, the heel reaches the eye or even the tip of the snout. The inner
metatarsal tubercle is feebly developed, very small and blunt; the outer
tubercle is absent.
That part of the thighs which is concealed by the legs when the animal is
at rest is whitish or pale greenish, marbled with dark olive, or bronze, or
of the latter colour with or without small light spots. No trace of yellow
is ever to be detected on that region, nor at the axillae or on the groin.
The vocal sacs are strongly pigmented with black, when inflated they are
pale grey. The iris is a mixture of black and gold.
{265}This form or race has the widest distribution, namely, all over Europe
with the exception of England, the northern half of France, the Rhine
countries, Denmark, and Italy. Southwards it extends from France through
Spain and Portugal into the Sahara, eastwards into Turkestan. It attains a
larger size than the others, but only in certain localities in various
countries, where circumstances favour its development. Eastern countries
produce the largest of all; those of the Volga are said to be very large.
German physiological laboratories prefer those from the Danube, from
Bohemia, and from the lakes and broad expansions of the Spree, to specimens
from other localities.
2. Var. _typica_ (_esculenta_, Linnaeus).–The heels just meet, but do not
overlap. The inner metatarsal tubercle is strong, compressed, and
prominent. A small outer tubercle is present. The heel reaches to the eye
or a little further; the hinder surface of the thighs is "marbled with
black, usually with more or less bright yellow pigment" in the living
specimens; the vocal sacs are white or feebly pigmented. This race inclines
to rather more green than the others, the males especially are often dark
grass-green, with scarcely any markings. The vertebral stripe is then
yellowish, and the lateral stripes almost golden. The range extends over
the whole of Central Europe and the kingdom of Italy. Its northern limit is
the southern end of Sweden. In the greater portion of Germany, Poland, and
Austria it overlaps the var. _ridibunda_, with which it does not seem to
pair, owing to a difference in the time of spawning; the var. _typica_
being about a fortnight later, and beginning to spawn when the other has
finished.
3. Var. _lessonae_, Camerano.–Except that the inner tubercle is stronger,
while the outer one is near the vanishing point, and that the fourth toe is
proportionally longer, this variety is really not distinguishable from the
typical form, and Boulenger himself confesses that the distinction is
arbitrary. The var. _lessonae_ seems to have a rather sporadic
distribution. It has been found in Piedmont and other parts of Italy, in
Hungary and Transylvania, near Vienna, Halle, Upper Bavaria, on the Rhine,
near Brussels, Paris, and what is of especial interest to us, in a few
places in the eastern counties of England.
According to Boulenger's "Notes on the Edible Frog in England,"[116] the
individuals of _R. esculenta_ which live in Foulmire {266}Fen in
Cambridgeshire, near Stow Bedon, and between Thetford and Scoulton in
Norfolk, and are generally supposed to have been introduced from France,
belong to the Italian form of var. _lessonae_. "It used to be found in
Cambridgeshire, in Foulmire Fen, where it was discovered in 1844; and
Bell[117] assures us that his father, who was a native of Cambridgeshire,
had noticed the presence of these frogs many years before at Whaddon and
Foulmire, where they were known from their loud croak as 'Whaddon organs'
and 'Dutch nightingales.' The species was afterwards rediscovered in
Norfolk, between Thetford and Scoulton, where it is now still very
abundant, and from inquiries made by Lord Walsingham, must have existed for
the last seventy (80) years at least. These frogs belong to the var.
_lessonae_, and differ widely (by the much stronger inner metatarsal
tubercle) from those found in a few other places in Norfolk, which are
undoubtedly the descendants of a number imported from France and Belgium in
1837, 1841, and 1842, and turned loose in the Fens at Foulden and in the
neighbourhood.... Within the last ten years large numbers of all the three
forms have been imported from Brussels, Berlin, and Italy, and liberated in
various localities in West Surrey and Hampshire. Berlin specimens of the
var. _ridibunda_ have also been introduced in Bedfordshire, and Italian
ones in Oxfordshire."[118]
Leaving aside the question whether the so-called var. _lessonae_ is merely
sporadically developed out of the typical form, the inquiry of the possible
origin of the English specimens of the var. _lessonae_ is of special
interest. Have they been introduced, as has been suggested, from Lombardy,
or are they the last lingering descendants of native English frogs? The
suggestion as to their Italian origin has naturally lost in value since
similar specimens have been found in Belgium and near Paris; but we must
remember that there existed considerable intercourse between East Anglia
and the monks of Lombardy, who, to mention only one instance, came
regularly to the old Priory of Chesterton, near Cambridge, in order to
collect their rents. If the frogs were introduced by them for culinary
purposes into various suitable localities their descendants would remain as
local as they, and as the undoubtedly introduced French typical specimens
actually are. On the other {267}hand, if we assume the _lessonae_ specimens
to be the last living descendants of English natives, it is inconceivable
why they should now be restricted to that eastern corner while there are
hundreds of other suitable places in England and Wales which, if on the
Continent, would be perfect paradises for Water-frogs. The same vegetation,
the same insects, the same climate, and–an enormous advantage to the
frogs–no storks.
These English specimens are "olive-brown or bronzy-brown above, with black
spots, strongly marked on the flanks, where a light longitudinal area
remains unspotted; glandular folds lighter; the sides of the head and the
ground colour of the flanks are sometimes green; tympanum chestnut-brown; a
pale yellow or pale green vertebral line, frequently edged with black; the
dark cross-bands on the limbs usually very irregular, sometimes absent;
lower surfaces more or less profusely spotted with blackish; iris golden.
Length of a male from Stow Bedon, 64 mm. or 2½ inches; of a female, 78 mm.
or 3 inches."[119]
4. Var. _chinensis_, Osb.–Distinguished by short glandular folds along the
back, in addition to the long dorso-lateral pair. The metatarsal tubercle
is large and shovel-shaped. Distribution from Corea and Japan to Siam.