coasts, the Common Seal and the Gray Seal. The former (Fig. 277) is
a constant resident in all suitable localities round the Scottish,
Irish, and English coasts, from which it has not been driven away by
the molestations of man. Although, naturally, the most secluded and
out-of-the-way spots are selected as their habitual dwelling-places,
there are few localities where they may not be occasionally met with.
Within the writers’ knowledge one was seen not many years ago lying on
the shingly beach at so populous a place as Brighton, and another was
caught in the river Welland, near Stamford, 30 miles from the sea. They
frequent bays, inlets, and estuaries, and are often seen on sandbanks
or mudflats left dry at low tide, and, unlike some of their congeners,
are not found on the ice-floes of the open sea, nor, though gregarious,
are very large numbers ever seen in one spot. The young are produced
at the end of May or beginning of June. They feed chiefly on fish, and
the destruction they occasion among salmon is well known to Scottish
fishermen. The Common Seal is widely distributed, being found not only on
the European and American coasts bordering the Atlantic Ocean, but also
in the North Pacific. It is from 4 to 5 feet in length, and variable in
colour, though usually yellowish-gray, with irregular spots of dark brown
or black above and yellowish-white beneath. The Gray Seal (_Halichœrus
grypus_) is of considerably larger size, the males attaining when fully
adult a length of 8 feet from nose to end of hind feet. It is of a
yellowish-gray colour, lighter beneath, and with dark gray spots or
blotches, but, like most other Seals, is liable to great variations of
colour according to age. This species appears to be restricted to the
North Atlantic, having been rarely seen on the American coasts, but not
farther south than Nova Scotia; it is chiefly met with on the coasts of
Ireland, England, Scotland, Norway, and Sweden, including the Baltic
and Gulf of Bothnia, and Iceland, though it does not appear to range
farther north. It is apparently not migratory, and its favourite breeding
places are rocky islands; the young being born in the end of September or
beginning of October.
Subfamily =Monachinæ=.—Incisors ²⁄₂. Cheek-teeth two-rooted, except the
first. On the hind feet the first and fifth toes greatly exceeding the
others in length, with nails rudimentary or absent.
_Monachus._[522]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁; total 32.
Crowns of molars strong, conical, compressed, hollowed on the inner side,
with a strongly marked lobed cingulum, especially on the inner side, and
slightly developed accessory cusps before and behind. The first and last
upper and the first lower molar considerably smaller than the others.
Vertebræ: C 7, D 15, L 5, S 2, C 11. All the nails of both fore and
hind feet very small and rudimentary. One species, _M. albiventer_, the
Monk-Seal of the Mediterranean and adjacent parts of the Atlantic.
The other genera[523] of this section have the same dental formula, but
are distinguished by the characters of the cheek-teeth and the feet. They
are all inhabitants of the shores of the southern hemisphere.
_Ogmorhinus._[524]—All the teeth of the cheek-series with three distinct
pointed cusps, deeply separated from each other; of these the middle or
principal cusp is largest and slightly recurved; the other two (anterior
and posterior) are nearly equal in size, and have their apices directed
towards the middle one. Skull much elongated. One species, _O. leptonyx_,
the Sea-Leopard, widely distributed in the Antarctic and southern
temperate seas.
_Lobodon._[525]—Cheek-teeth with much-compressed elongated crowns and a
principal recurved cusp, rounded and somewhat bulbous at the apex, and
one anterior, and one, two, or three posterior, very distinct accessory
cusps. One species, _L. carcinophaga_.
_Pœcilophoca._[526]—Cheek-teeth small, with simple, subcompressed,
conical crowns, having a broad cingulum, but no distinct accessory cusps.
One species, _P. weddelli_.
_Ommatophoca._[527]—All the teeth very small; those of the cheek-series
with pointed recurved crowns, and small posterior and still less
developed anterior accessory cusps. Orbits very large. Nails quite
rudimentary on front, and absent on hind feet. The skull bears a
considerable resemblance to that of the members of the next subfamily,
towards which it may form a transition. There is one species, _O. rossi_,
of which very little is known.
Subfamily =Cystophorinsæ=.—Incisors ²⁄₁. Teeth of cheek-series generally
one-rooted. Nose of males with an appendage capable of being inflated.
First and fifth toes of hind feet greatly exceeding the others in length,
with prolonged cutaneous lobes, and rudimentary or no nails.
_Cystophora._[528]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ¹⁄₁; total
30. The last molar has generally two distinct roots. Beneath the skin
over the face of the adult male, and connected with the nostrils, is a
sac which, when inflated, forms a kind of hood covering the upper part of
the head. Nails present, though small, on the hind feet. One species, _C.
cristata_, the Hooded or Bladder-Nose Seal of the Polar Seas.
_Macrorhinus._[529]—Dentition as the last, but cheek-teeth of simpler
character, and all one-rooted. All the teeth, except the canines, very
small relatively to the size of the animal. Hind feet without nails.
Vertebræ: C 7, D 15, L 5, S 3, C 11. Nose of adult male produced into a
short tubular proboscis, ordinarily flaccid, but capable of dilatation
and elongation under excitement. One species, _M. leoninus_, the
Elephant Seal, or Sea-Elephant of the whalers, the largest of the whole
family, attaining the length of nearly 20 feet. Formerly abundant in the
Antarctic Seas, and also found on the coast of California.
_Extinct Seals._—Remains of animals of this group have been found in late
Miocene and Pliocene strata in Europe and America, the most abundant and
best-preserved being those of the Pliocene Antwerp Crag, the subject of
an illustrated monograph by Van Beneden. Nothing has, however, yet been
discovered which throws any light upon the origin of the group, since
all the extinct forms at present known come within the definition of
the existing families; and, though annectant forms between these occur,
there are as yet no transitions to a more generalised type of mammal.
Indeed, all those of which the characters are best known belong to the
completely developed Phocine or Trichechine, and not to the Otariine,
type. The typical genus _Phoca_ occurs in the Antwerp Crag, while remains
of Seals provisionally referred to this genus are found in the Pliocene
of the Crimea and the Miocene of Malta and Virginia. Of the other
Antwerp forms _Callophoca_ is said to be allied to _Phoca grœnlandica_,
_Platyphoca_ to _Phoca barbata_, _Phocanella_ to _Phoca foetida_,
_Gryphoca_ to _Halichœrus_, _Palæophoca_ and _Monatherium_ to _Monachus_,
and _Mesotaria_ to _Cystophora_; while _Prophoca_ does not appear to
come very close to any existing form. It should be observed that it is
extremely doubtful whether all these fossil Seals are really entitled to
generic distinction.
_Bibliography of Pinnipedia._—J. A. Allen, _History of North
American Pinnipeds_, 1880; St. George Mivart, “Notes on the
Pinnipedia,” _Proc. Zool. Soc._ 1885, p. 484; P. J. Van
Beneden, _Ossements fossiles d’Anvers_, in the _Mém. Acad. Roy.
d. Belgique_.
_Suborder_ CREODONTA.
The discovery of fossil remains in Eocene and early Miocene formations
both in Europe and North America shows that numerous species of
terrestrial carnivorous animals existed upon the earth during those
periods which cannot be referred to either of the sections into which
the order has now become broken up. By some zoologists these have been
supposed to be Marsupials, or at least to show transitional characters
between the Metatherian and Eutherian subclasses. By others they are
looked upon as belonging altogether to the latter group, and as the
common ancestors of existing Carnivores and Insectivores, or perhaps
rather as descendants or relatives of such common ancestors, retaining
more of the generalised characters than any of the existing species. They
shade off almost insensibly into numerous other forms less distinctly
carnivorous, to the whole of which, including the modern Insectivora,
Cope (to whom we are indebted for much of our knowledge of the American
extinct species) gives the name of BUNOTHERIA, those more specially
related to the existing Carnivora forming the suborder Creodonta. These
are instances, however, in which the application of the principles of
classification adopted in the case of existing species, of which the
entire structure is known, and which have become divided into isolated
groups by the extinction of intermediate forms, is almost impossible.
If the generally accepted view of evolution is true, and the extreme
modifications pass insensibly into each other by minute gradations (a
view the palæontological proof of which becomes strengthened by every
fresh discovery), there must be many of these extinct forms which cannot
be assigned to definitely characterised groups. There are, however, some
which stand out prominently from the others as formed on distinct types,
having no exact representatives at present living on the earth.
[Illustration: FIG. 278.—Anterior portion of the skull of _Hyænodon
leptorhynchus_. (After Filhol.)]
The more typical Creodonts appear, however, to be so closely related to
the true Carnivora through the extinct _Miacidæ_ (p. 539), that it is on
the whole advisable to regard them as representing a distinct suborder
of Carnivora. In the strong development of the canines (Fig. 278) they
are distinguished from the modern Insectivora; and they also differ from
the latter and resemble the true Carnivores in the form of the incisors,
the second one in the lower jaw (when three are present) being thrust
up above the level of the other two in the manner obtaining in most of
the modern Carnivora. Some of the most generalised forms included in the
present group approximate so closely to the Condylarthrous Ungulates as
to indicate that both groups have probably had a common origin.
The Creodonta as a whole are characterised by the small size of the
brain, the absence of a single differentiated carnassial tooth, and the
triangular form or secant character of their upper molars. In the carpus
the scaphoid and lunar were usually distinct; the femur has a third
trochanter; the upper or tibial surface of the astragalus usually wants
the groove found in modern Carnivores: and the feet were plantigrade. The
curious resemblance of the molars of many of these forms to those of the
Marsupials may indicate a genetic relationship between the two groups;
but, on the other hand, the presence of a full set of milk-teeth and the
absence of palatal vacuities, or of an inflection of the angle of the
mandible, sharply distinguishes them from that order. Space permits of a
notice only of the more interesting forms.
_Hyænodontidæ._—This family is taken to include some of the more
specialised types, such as the European and American _Hyænodon_ and
_Oxhyæna_ and the European _Pterodon_. In _Hyænodon_ (Fig. 278) the
dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₃; the fourth premolar
above and the first true molar below being formed upon the “carnassial”
plan, but the teeth behind these, instead of being tuberculated as in all
existing Carnivora, repeat the characters of the carnassial, and also
increase in size, especially in the lower jaw, from before backwards.
The last lower molar differs from the two preceding teeth, and is very
like the carnassial of _Felis_. The scaphoid and lunar of the carpus
were fused together. Some species, as _H. leptorhynchus_, were as large
as a Wolf, while others did not exceed a Fox in size. _Pterodon_ is
readily distinguished by having _m_ ³⁄₃, by the larger size of the inner
tubercles of the upper molars, and the similarity in the form of the
three lower molars. In some species there were only two upper incisors,
and the first lower premolar may be wanting. _Oxhyæna_ is a specialised
form with _i_ ²⁻³⁄₀, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂, and a very long
mandibular symphysis.
_Proviverridæ._—The European and American genus _Proviverra_
(_Cynohyænodon_ or _Stypolophus_) may be regarded as representing a
second family. The dental formula in this genus is the typical _i_
³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃, the upper molars have a large inner
tubercle, while the lower molars are differentiated into a blade and
talon, the blade having a large inner cusp. The upper teeth closely
resemble the molars of _Dasyurus_, while the lower molars are like the
lower carnassial of _Cynodictis_ and _Viverra_; and thus indicate how the
Creodonts may have passed into the true Carnivores through the extinct
_Miacidæ_.
[Illustration: FIG. 279.—The three right upper molars of _Arctocyon
dueli_ (_a_), and the second of _A. gervaisi_ (_b_); from the lowest
Eocene of Rheims. _pr_, protocone; _pa_, paracone; _me_, metacone; _hy_,
hypocone; _ml_, metaconule; _pl_, paraconule. (From Osborn.)]
_Arctocyonidæ and Mesonychidæ._—The first of these families is
represented by _Arctocyon primævus_, one of the oldest known Tertiary
mammals, from the lowest Eocene beds of La Fère, department of Aisne,
France, and also by other species from corresponding beds at Rheims. The
dental formula is _i_ ³⁄₃, _c_ ¹⁄₁, _p_?⁄₃₋₄, _m_ ³⁄₃. The upper molars
(Fig. 279) are tritubercular, with an incipient postero-internal column
(hypocone); the lower are quadritubercular; and the premolars simple.
The typical species was of large size, but the two of which the teeth
are figured were considerably smaller. In the American _Mesonyx_ the
dental formula was the typical one, the jaws were comparatively short,
the mandibular symphysis was elongated, the cheek-teeth were of simple
structure, and resembled the premolars of many of the true Carnivora,
and the astragalus had a grooved tibial surface and distinct distal
facets for the cuboid and navicular, resembling in the latter respect the
corresponding bone of a Perissodactyle Ungulate. The terminal phalanges
had deeply fissured extremities, and are said to be more like those of
Rodents than true Carnivores. _Mesonyx ossifragus_ was larger than a
Grizzly Bear. _Amblyctonus_, of the same deposits, differs by the smooth
tibial face of the astragalus and the development of an anterior cusp to
the lower molars.
CHAPTER XII
THE ORDER INSECTIVORA
[Illustration: FIG. 280.—Right lateral aspect of the anterior portion of
the cranium of _Erinaceus collaris_. Enlarged. (From Dobson, _Proc. Zool.
Soc._ 1881, p. 403.)]
The Insectivora comprise a number of comparatively small mammals,
generally of terrestrial, although rarely of arboreal or aquatic habits,
and presenting the following common features. They are unguiculate, and
have plantigrade or subplantigrade, and generally pentadactylate feet, in
which the pollex and hallux are not opposable to the other digits. They
are diphyodont and heterodont, and the teeth are rooted. The molars are
studded with sharp cusps, the crowns of the upper molars being either
quadrangular or triangular; there are never less than two incisors in
either side of the mandible; and in many cases the incisors, canines, and
anterior premolars are not clearly differentiated from one another (Fig.
280); the canines being usually weak. Clavicles are present, except in
_Potamogale_. The body is clothed with fur or protected by an armature
of spines; the testes are inguinal or placed near the kidneys, and are
not received into a scrotum; the penis is pendent or suspended from the
wall of the abdomen; the uterus is two-horned and with or without a
distinct corpus uteri; the placenta is discoidal and deciduate; and the
smooth cerebral hemispheres do not extend backwards over the cerebellum
(Fig. 281). The projection of the muzzle far beyond the extremity
of the lower jaw is a very general feature. The humerus generally
has an entepicondylar foramen. Certain forms, such as _Talpa_ and
_Galeopithecus_, are unique among mammals in having ossified intercentra
in the dorso-lumbar region of the vertebral column.
Representatives of this order are found throughout the temperate and
tropical parts of both hemispheres (except South America and Australia),
and exhibit much variety both in organisation and in habits. With the
exception of the _Tupaiidæ_, all are nocturnal; the greater number
are cursorial, but some (_Talpa_, _Chrysochloris_, _Oryzorictes_) are
fossorial; some (_Potamogale_, _Nectogale_, _Myogale_) are natatorial,
and a few (_Tupaiidæ_) arboreal; while the species of the aberrant
genus _Galeopithecus_ glide through the air like the Flying Squirrels.
To the great majority the term insectivorous is strictly applicable,
_Galeopithecus_ alone being phytophagous; while _Potamogale_ is said to
feed on fish, and the different species of Moles live chiefly on worms.
The general organisation of the Insectivora indicates a very low type,
and were it not for the specialised character of their placentation and
the tendency to lose the differentiated characters of the anterior teeth
they might be regarded as closely allied to the ancestral type of many of
the heterodont mammals. The strongly marked distinction of the canines
from the incisors and anterior premolars in the Mesozoic and most of
the Tertiary mammals (excepting some of the Ungulates) points, however,
very decidedly to the conclusion that the want of definition between
these teeth in many of the modern Insectivora is an acquired feature.
Fossil forms apparently indicate a relationship on the one hand with the
Creodont Carnivora, and on the other with the Lemuroid Primates; indeed
it is in some instances impossible to say whether extinct genera are
really Insectivores or Lemuroids.
[Illustration: FIG. 281.—Upper surface of the brain of _Tupaia
ferruginea_. (From Garrod, _Proc. Zool. Soc._ 1879, p. 304.)]
In most Insectivora the cranial cavity is of small relative size, and
in none is the brain-case elevated to any considerable extent above the
facial line. The facial part of the skull is generally much produced,
and the premaxillary and nasal bones are well developed. The zygomatic
arch is usually slender or deficient, the latter being the case in most
of the species; and postorbital processes of the frontals are found only
in the _Galeopithecidæ_, _Tupaiidæ_, and _Macroscelididæ_. The number
of dorsal vertebræ varies from 13 in _Talpa_ to 19 in _Centetes_; that
of the lumbar from 3 in _Chrysochloris_ to 6 in _Talpa_ and _Sorex_;
and of the caudal from the rudimentary series of 8 in _Centetes_ to the
40 or more of _Microgale_. Not less variable are the characters of the
vertebræ themselves; the spinous processes often being very long in one
and short in another species of the same genus. In the _Soricidæ_ and
_Myogale_ the neural arches of the cervical vertebræ are very slender.
In the _Soricidæ_ and _Gymnura_ the four anterior vertebræ develop large
single hypapophyses. In _Galeopithecus_ the centrum of each vertebra
supports posteriorly a pair of intercentral ossifications; while in
_Erinaceus_, _Myogale_, and _Talpa_ small oval ossicles are found on
the inferior surfaces of the lumbar interspaces. In _Erinaceus_, owing
to the thickness of the neural cord in the cervical region and its
abrupt termination, the diameter of the neural canal in the cervical
and first two dorsal vertebræ greatly exceeds that of any of the
succeeding vertebræ. The sternum is variable, but generally narrow,
bilobate in front, and divided into segments. The pectoral girdle
presents some remarkable adaptive modifications, most fully expressed
in _Talpa_, having relation to the use of the fore limbs in burrowing;
but in the Golden Moles (_Chrysochloris_) the forearm and manus alone
become specially modified for this purpose. In _Galeopithecus_ and
_Macroscelides_ the bones of the forearm (radius and ulna) are distally
united. The manus has generally five digits, but in _Rhynchocyon_ and
in one species of _Oryzorictes_ the pollex is wanting, while in the
true Moles it is extremely modified. The femur has, in most species,
a prominent ridge below the greater trochanter representing a third
trochanter. In _Galeopithecus_, _Tupaia_, _Centetes_, _Hemicentetes_,
_Ericulus_, and _Solenodon_ the tibia and fibula are distinct, but in all
the other genera more or less united together. The pes usually possesses
five digits (rarely four by reduction of the hallux); and in some forms,
as in the leaping species (_Macroscelides_, _Rhynchocyon_), the tarsal
bones are greatly elongated. The form of the pelvis, and especially of
the symphysis pubis, varies within certain limits; and these differences
have been proposed by Leche as a basis for the classification of the
families. Thus in the _Galeopithecidæ_, _Tupaiidæ_, and _Macroscelididæ_
there is a long symphysis; in the _Erinaceidæ_, _Centetidæ_, and
_Potamogalidæ_ the symphysis is short; and in the _Soricidæ_, _Talpidæ_,
and _Chrysochloridæ_ there is none.
Space does not admit of attempting a sketch of the modifications of the
muscular system, which will be found fully described in Dr. Dobson’s
_Monograph_, referred to in the bibliography. As to the nervous system,
it has been already mentioned that the brain throughout the order
presents a low type of organisation; in none of the members do the
cerebral hemispheres present any trace of convolutions, nor do they
extend backwards so as to cover the cerebellum, while the olfactory
lobes are large and project in front, and the corpus callosum is short
and thin. In the Hedgehogs (_Erinaceus_) the spinal column ends abruptly
opposite the third or fourth dorsal vertebra in a slender filament,
and the dorsal and lumbar nerves, given off in front of this point,
are carried backwards in two compressed bundles occupying the suddenly
narrowed spinal canal as far as the sacrum.
Owing to the similarity in the character of the food, the truly
insectivorous species, forming more than nine-tenths of the order,
present little variety in the structure of their digestive organs. Except
in _Galeopithecus_ the stomach is a simple, thin-walled sac; but in some,
as in _Centetes_ and allied genera, the pyloric and œsophageal openings
are very close together. The intestinal canal has much the same calibre
throughout, and varies from three (in the Shrews) to twelve times (in
the Hedgehogs) the length of the head and body. In the arboreal genera,
_Galeopithecus_ and _Tupaia_, as well as in the _Macroscelididæ_, all of
which probably feed in part on vegetable substances, most of the species
possess a cæcum. The liver is deeply divided into lobes, the right and
left lateral being cut off by deep fissures; and both the caudate and
Spigelian lobes being generally well developed. The gall-bladder, which
is usually large and globular, is placed on the middle of the posterior
surface of the right central lobe.
In most of the members of the order (_Soricidæ_, _Centetidæ_,
_Chrysochloridæ_) the penis is capable of being more or less completely
retracted within the fold of integument surrounding the anus; in some
(_Galeopithecidæ_, _Talpidæ_) it is pendent in front of the anus; while
in others (_Macroscelididæ_, _Erinaceidæ_, _Solenodontidæ_) it is
carried forwards and suspended from the abdominal wall. In the subfamily
_Centetinæ_ and _Chrysochloris_ the testes lie immediately behind the
kidneys, but in others more or less within the pelvis. During the rutting
season they become greatly enlarged, forming protrusions in the inguinal
region. Except in _Rhynchocyon_ the uterine cornua are long and open
into a short corpus uteri, which in many species (_Soricidæ_, _Talpidæ_,
_Centetidæ_, _Chrysochloridæ_) is not separated from the vagina by a
distinct os uteri. With the exception of _Galeopithecus_ all Insectivora
appear to be multiparous, the number of young at a birth varying from two
to eight in _Erinaceus_, and from twelve to twenty in _Centetes_. The
position of the mammary glands and the number of the teats vary greatly.
Thus in _Galeopithecus_ there are two pairs of axillary teats, and in
_Solenodon_ a single post-inguinal pair; but in most species they range
from the thorax to the abdomen, varying from two pairs in _Gymnura_ to
twelve in _Centetes_. In _Chrysochloris_ the thoracic and inguinal teats
are lodged in deep cup-shaped depressions.
Odoriferous glands exist in many species. In most Shrews these glands
occur on the sides of the body at a short distance behind the axilla,
and their exudation is probably protective, since few carnivorous
animals will eat the dead bodies of these creatures. In both species of
_Gymnura_ and in _Potamogale_ large pouches are situated on either side
of the rectum and discharge their secretions by ducts, opening in the
first-named genus in front of, and in the latter within the margin of the
anus. In _Centetes_ the ducts of similarly situated racemose glands open
by pores at the bottom of deep pits placed at either side of the anus.
The integument is thin, but in many species is lined by a muscular coat,
which is probably more developed in the Hedgehogs (_Erinaceidæ_) than in
any other mammal. In this family and the _Centetidæ_ most of the species
are protected by spines implanted in the panniculus carnosus muscle, and
more or less replacing the fur of the upper surface of the body.
The order is usually divided into two suborders, but the very aberrant
genus which constitutes the first might well be raised to ordinal rank.
It has little in common with the true Insectivora, but as it certainly
belongs to no other of the recognised mammalian orders it is retained
among them chiefly to avoid the inconvenience of increasing the number of
ordinal divisions for the sake of a single isolated form.
_Suborder_ DERMOPTERA.
Upper and lower incisors compressed, multicuspidate, the lower deeply
pectinated; fore and hind limbs connected by a broad integumentary
expansion forming a parachute.
_Family_ GALEOPITHECIDÆ.
In addition to the characters given under the head of the suborder it may
be mentioned that the orbit is nearly surrounded by bone, the zygomatic
arches are well developed, the tympanic forms a bulla, the ulna is
distally united with the radius, the tibia and fibula are distinct, the
pubic symphysis is long, the penis is pendent, the testes are received
into inguinal pouches, the mammæ are axillary, the uterus is two-horned,
and there is a large cæcum.
_Galeopithecus._[530]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃;
total 34. Second upper incisor and canine with two roots. Two species—_G.
volans_ and _G. philippinensis_. The former, which is distinguished
from the latter by the form of the upper incisors, has a total length
of nearly 2 feet. The long and slender limbs are connected by a broad
integumentary expansion extending outwards from the sides of the neck
and body, and forming also a web between the fingers and toes as far as
the base of the claws (Fig. 282); the hind limbs are further connected by
a similar expansion passing outwards along the back of the feet to the
base of the claws, and, inwardly, involving the long tail to the tip,
forming a true interfemoral membrane, as in the Bats.
The two species of Flying Lemurs, as the representatives of this genus
are commonly but erroneously called, live in the forests of the Malay
Peninsula, Sumatra, Borneo, and the Philippine Islands, where they feed
chiefly on the leaves and fruits of trees. Their habits are nocturnal,
and during the daytime they cling to the trunks or limbs of trees, head
downwards, in a state of repose. With the approach of night their season
of activity commences, when they may be seen gliding from tree to tree
supported on their cutaneous parachute, and they have been observed to
traverse in this way a space of 70 yards with a descent of only about one
in five.
[Illustration: FIG. 282.—Feet of _Galeopithecus philippinensis_.]
_Galeopithecus_ was referred by some of the older zoologists and
anatomists to the Bats, and by others to the Lemurs, but Professor
Peters’s view, that it belongs to neither of these orders, and should be
considered an aberrant Insectivore, has been very generally accepted,
although, as mentioned above, the association is by no means a close one.
Besides differing from the Bats in the form of the anterior limbs and of
the double-rooted outer incisor and canine, it also contrasts strongly
with them in the presence of a large sacculated cæcum, and in the great
length of the colon, which is so remarkably short in all the Chiroptera.
From the Lemurs, on the other hand, the form of the brain, the characters
of the teeth, the structure of the skull, and the deciduate discoidal
placenta completely separate it. In a recent elaborate memoir on the
myology and affinities of _Galeopithecus_ Dr. Leche[531] considers that
we have in this genus an indication of the mode in which the Insectivora
were modified into the Chiroptera, although it is completely off the
direct line of descent. The deeply pectinated crowns of the lower
incisors of _Galeopithecus_ are quite unique in the class, and the only
approach to the double-rooted canine, except in _Erinaceus_ and _Talpa_,
is found among the Marsupials in _Perameles_, where the root of the
canine is grooved.
_Suborder_ INSECTIVORA VERA.
Upper and lower incisors conical, unicuspidate or with basal cusps only,
the lower not pectinated; limbs free, formed for terrestrial progression.
The following table gives a key to the distinctive characters of the
existing families:—
I. Upper molars broad, multicuspidate, with more or less
well-defined W-shaped crowns.
A. Symphysis pubis long; generally a cæcum; cerebral cavity
comparatively large.
_a._ Orbit encircled by bone; metatarsus moderate; arboreal.
_Tupaiidæ_.
_b._ Orbit not encircled by bone; metatarsus greatly elongated;
terrestrial. _Macroscelididæ._
B. Symphysis pubis short or none; no cæcum; cerebral cavity
small; skull without postorbital processes.
_a._ First and second upper molars with a central fifth cusp.
_a′._ Tympanic annular, not forming a bulla. _Erinaceidæ._
_b._ No central fifth cusp to upper molars.
_a′._ Tympanic annular, not forming a bulla; no zygomatic
arch. _Soricidæ._
_b′._ Tympanic forming a bulla; zygomatic arch developed.
_Talpidæ._
II. Upper molars narrow, with V-shaped crowns.
_a′._ Tympanic annular, not forming a bulla; zygomatic
arch imperfect.
_a″._ No clavicles. _Potamogalidæ._
_b″._ Clavicles well developed.
_a‴._ Skull constricted between the orbits;
penis suspended. _Solenodontidæ._
_b‴._ Skull not constricted; penis pendent,
retractile. _Centetidæ._
_b′._ Tympanic forming a bulla; zygomatic arch well
developed. _Chrysochloridæ._
The second section, in which the molars are of the primitive
tritubercular type, should probably be regarded as containing the most
generalised representatives of the order; and it is noteworthy that the
whole of them are confined to Africa, Madagascar, and the West Indies,
whereas most of the first section are widely distributed over the
Palæarctic and Oriental regions. None of the existing families of the
second section are known in a fossil condition, although it is suggested
that the extinct _Leptictidæ_ includes allied types.
_Family_ TUPAIIDÆ.
Skull with comparatively large brain-case, orbit surrounded by bone,
well-developed zygomatic arch, perforated jugal, and a tympanic bulla.
Upper molar broad, with cusps arranged in a W. Pubic symphysis long;
radius and ulna, and tibia and fibula separate; metatarsus only slightly
longer than tarsus. Usually a short cæcum. Habits arboreal and diurnal.
Confined to the Oriental region.
[Illustration: FIG. 283.—The Pentailed Tree-Shrew (_Ptilocercus lowi_).
From Gray, _Proc. Zool. Soc._ 1848. ½ natural size.]
_Tupaia._[532]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
38. Feet naked beneath, the sole furnished with projecting pads; claws
moderate, curved, and sharp; head pointed; ears rounded; tail bushy,
distichous, with short hair below. The Tree-Shrews, of which there are
some nine species, are found in India, Burma, the Malay Peninsula,
the Nicobars, Sumatra, Java, and Borneo. The species closely resemble
one another, differing chiefly in size and in the colour and length of
the fur. Their general appearance is very Squirrel-like. Their food
consists of insects and fruit, which they usually seek in the trees, but
also occasionally on the ground. When feeding they often sit on their
haunches, holding the food, after the manner of Squirrels, between their
forepaws.
_Ptilocercus._[533]—Represented only by the Pentailed Tree-Shrew (_P.
lowi_, Fig. 283) of Borneo, in which the tail is of extraordinary length,
with the proximal two-thirds naked, and the remaining third furnished
with a bilateral fringe of long hairs, from which the genus takes its
name.
_Extinct Genera._—An Insectivore from the Middle Miocene of France,
described as _Lantanotherium_, is said to be nearly allied to _Tupaia_.
The genus _Parasorex_, from strata of similar age, has the dental formula
_i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃, and is regarded as connecting the
present with the following family.
_Family_ MACROSCELIDIDÆ.
Skull with comparatively large brain-case, strong zygomatic arch, a
tympanic bulla, orbit surrounded by bone, imperforate jugal, and usually
no postorbital process. Molars broad, with four cusps arranged in a W.
Pubic symphysis long; proximal end of tibia and fibula united; radius
and ulna united or separate; metatarsus much longer than tarsus. A large
cæcum. Habits terrestrial, saltatorial, and nocturnal. The family is
confined to Africa.
_Macroscelides._[534]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂₋₃;
total 40 or 42. Distal extremity of radius and ulna united. Five digits
in manus, and five or four in pes. This genus, which is taken to include
_Petrodromus_, comprises ten species widely distributed throughout the
African continent. All are closely related, resembling one another
in general form, and even in the colour of the fur. They fall into
two groups, distinguished by the presence or absence of a small third
lower molar.[535] _M. tetradactylus_ (Fig. 284), the type of the genus
_Petrodromus_, differs from all the other species in the absence of the
hallux, and of the third lower molar. These animals are commonly known
as Jumping Shrews, and, like the following genus, have the muzzle much
produced.
_Rhynchocyon._[536]—Dentition: _i_ ¹⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ²⁄₂;
total 36. Upper incisor frequently shed in the adult. Radius and ulna
distinct; hind limbs relatively shorter, and proboscis longer than in the
type genus; four digits in each foot. Four closely allied species have
been described from East Africa. The head and body of the type species
measures about 8 inches in length; and the long tail is covered with a
ringed skin, sparsely haired. Its habits are fossorial.
[Illustration: FIG. 284.—_Macroscelides tetradactylus._ × ½. (From
Peters, _Reise nach Mossambique._)]
_Family_ ERINACEIDÆ.
Skull with a small brain-case; no postorbital process; slender and
occasionally imperfect zygomatic arch, and an annular tympanic, which
does not form a bulla. Upper molars with four principal cusps and a small
central median cusp. Acromion of scapula bifid; pubic symphysis short;
radius and ulna free, but tibia and fibula united proximally. No cæcum;
penis carried forward and suspended from the wall of the abdomen. Habits
terrestrial. Found in the Palæarctic, Ethiopian, and Oriental regions.
Subfamily =Gymnurinæ=.—Palate completely ossified; pelvis very narrow;
fur without spines.
_Gymnura._[537]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total 44.
This genus, if _Hylomys_ is rightly included, is represented by the two
species, _G. rafflesi_ and _G. suilla_, from the Malay Peninsula and
Indian Archipelago. The former has the appearance of a large Rat with
a long tail and head and projecting mobile snout; the latter, which is
much smaller, with a short tail and small third upper premolar, has long
been known under the name of _Hylomys suillus_, and classed with the
_Tupaiidæ_. Both species present a very generalised type of dentition,
in this respect occupying an almost central position in the order.
_G. suilla_ is represented in Mount Kina-Balu, Borneo, by a variety
characterised by the presence of a dark dorsal streak. Many zoologists
prefer to retain _Hylomys_ as a distinct genus.
Subfamily =Erinaceinæ=.—Palate imperfectly ossified; pelvis wide; fur
with spines.
_Erinaceus._[538]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃; total
36. The first pair of upper incisors (Fig. 285) are considerably larger
than the others, and are widely separated from one another in the middle
line; the canine is very similar to the third incisor; and, except
in _E. europæus_ (Fig. 285), each of these teeth is inserted by two
distinct roots (Fig. 280, p. 610). The first lower incisor is large and
proclivous. The number of vertebræ is C 7, D 15, L 6, S 3, C 11.
[Illustration: FIG. 285.—Right lateral aspect of the anterior portion of
the skull of the Hedgehog (_Erinaceus europæus_). Enlarged. (From Dobson,
_Proc. Zool. Soc._ 1881, p. 403.)]
The Hedgehogs comprise nearly twenty species, distributed throughout
Europe, Africa, and the greater part of Asia, but not found in
Madagascar, Ceylon, Burma, Siam, the Malay Peninsula, or Australia. All
the species resemble one another in the armature of spines investing the
upper surface and sides of the body; and all possess the power of rolling
themselves up into the form of a ball, protected on all sides by the
strong spines; the dorsal integument being brought downwards and inwards
over the head and tail, so as to include the limbs also, by the action of
special muscles. The common Hedgehog (_E. europæus_) is the most aberrant
species, differing from all the rest in the peculiarly shaped and
single-rooted third upper incisor and canine (Fig. 285), and in its very
coarse, harsh fur. The dentition of the long-eared North Indian form,
_E. collaris_ (Fig. 280), may be considered characteristic of all the
other species, the only important differences being found in the variable
size and position of the second upper premolar, which is very small,
external, and deciduous in the Indian _E. micropus_ and _pictus_. The
former species, limited to South India, is further distinguished by the
absence of the jugal bone. Of the African species, _E. diadematus_, with
long frontal spines, is probably the commonest; while _E. albiventris_
has been made the type of a separate genus on account of the total
absence of the hallux.
The well-known European species feeds on insects, worms, slugs, mice,
rats, lizards, snakes, etc., as well as on eggs, fruit, and roots. It
hibernates during the winter. The young are usually produced in July
or August in litters of not more than four, but there may be a second
litter in October; and the period of gestation is believed not to exceed
a month. The Indian, and probably also the African species, do not
hibernate.
The existing _E. europæus_ dates from the Pleistocene period, and extinct
species of the genus are found in the Upper and Middle Miocene of the
Continent.
_Extinct Genera._—The French Lower Miocene genus, _Palæoerinaceus_,
appears to be allied to _Erinaceus_, but is distinguished by the
wider and completely ossified palate. In the Upper Eocene of Central
France there are two genera, which appear to be most nearly allied to
_Gymnura_, although connected by _Palæoerinaceus_ with _Erinaceus_. Of
these _Necrogymnurus_,[539] with which _Cayluxotherium_ is apparently
identical, has teeth like _Gymnura_, but an imperfectly ossified palate
like _Erinaceus_; and the skull is remarkable for the peculiar rugose
structure of the parietal and temporal regions. _Comphotherium_ is
distinguished by the presence of a cingulum to the lower molars, like
that found in _Gymnura_.
_Family_ SORICIDÆ.
Skull (Fig. 286) long and narrow, with no zygomatic arch or postorbital
process, and the tympanic ring-like and not forming a bulla. Upper molars
with the cusps arranged in a distinct W. No pubic symphysis. The tibia
and fibula united. No cæcum. Habits usually terrestrial, rarely aquatic.
Distribution extensive.
The Shrews are Rat-like or Mouse-like insectivores, with the body covered
with hair, and the muzzle long and pointed. Their dentition (Fig. 286)
is peculiar and characteristic. Thus the first upper incisor is large
and hook-like, with a more or less developed basal cusp on the posterior
border. Between this and the last premolar there are a variable number
of small teeth, representing the other incisors, the canine, and the
anterior premolars; although, owing to the early obliteration of the
maxillo-premaxillary suture, their homology is exceedingly difficult to
determine. Three molars are invariably present, of which the third is
much the smallest. In the mandible there are always six teeth, but in one
species of _Myosorex_ there may be a seventh. The first lower incisor
is usually directed horizontally forwards; the second incisor (formerly
reckoned as the canine) is the smallest tooth of the series, the fourth
premolar being slightly larger.
This family, which includes considerably more than half the
representatives of the order, has a distribution coextensive with the
latter. Many classifications of this difficult group have been attempted,
but according to the latest proposal of Dr. Dobson,[540] the genera may
be divided into two subfamilies, distinguished by the apparently trivial
character of the colour of the teeth.
[Illustration: FIG. 286.—Left lateral view of the cranium and mandible
of _Sorex veræpacis_. In the cranium—_i_, first incisor; _c_, fourth
incisor; _p_, canine; _m_, fourth premolar: in the mandible—_i_, first
incisor; _c_, second incisor; _p_, fourth premolar; _m_, first molar.
(From Alston, _Proc. Zool. Soc._ 1877.)]
Subfamily =Soricinæ=.—Summits of the teeth coloured red.
_Sorex._[541]—Dentition: _i_ ⁴⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total 32.
Openings of male and female generative organs separated from the anal
orifice; penis cylindrical or tapering; ear well developed; tail long,
covered with equal or subequal hairs.
It has been shown by Brandt that the position of the premaxillo-maxillary
sutures in the type of the genus is between the fourth and fifth tooth,
so that it appears that we must regard this genus as differing from all
other Eutherian mammals in having four upper incisors. Dr. Dobson, in
his paper quoted, classes the tooth here reckoned as the upper canine
with the premolar series in all the Shrews. Habits terrestrial. Species
numerous, inhabiting the Palæarctic and Nearctic regions.
Of the two species found in the British Isles the Common Shrew (_S.
vulgaris_, Fig. 287) is by far the most common in England, and is about
the size of the House Mouse, to which it approximates in general form.
The body is clothed with close long fur, very soft and dense, and varying
in colour from light reddish to dark brown above, rarely speckled or
banded with white. The under surface of both the body and the tail is
grayish. The basal four-fifths of all the hairs above and beneath are
dark bluish-gray; the hairs of the tail are less densely set and coarser.
On each side of the body, at a point about one-third of the distance
between the elbow and the knee, may be found, especially in the rutting
season, a gland covered by two rows of coarse hairs. This secretes a
peculiar fluid, on which the odour of the animal depends; this odour
being evidently protective, and rendering the creature secure against the
attacks of many predaceous animals.
The geographical range of the Common Shrew is exceedingly wide, extending
eastwards through Europe and Asia (north of the Himalayas) to North
America.
[Illustration: FIG. 287.—The Common Shrew (_Sorex vulgaris_).]
The Lesser Shrew (_S. pygmæus_[542]) is far less common in England and
Scotland, although more abundant in Ireland, where _S. vulgaris_ is
unknown. It is distinguished from the latter not only by its inferior
dimensions, but also by the circumstance that the third upper incisor is
not longer than the fourth, and by the considerably shorter length of the
forearm and manus. This species extends through Europe and Asia as far
as the inland of Saghalin. Both this and the preceding species generally
live in wooded districts, making their nests under the roots of trees, or
in slight hollows. The great mortality noticeable among the Shrews in the
early part of the autumn is probably due to insufficiency of food. The
breeding season extends from the latter part of April to the beginning of
August. The young, which are blind, naked, and toothless at birth, are
very quickly developed. The number in a litter is usually from five to
seven, but may be as many as ten.
The Alpine Shrew (_S. alpinus_), which is restricted to the Alpine region
of Central Europe, is slightly larger than the common species, from which
it is distinguished by the longer tail, the length of which exceeds that
of the head and body, by the fur being dark on both surfaces of the body,
and also by the larger size of the upper canine.
In North America _S. bendirei_ is by far the largest species of the
genus; and, as in many other species of the same country, the fourth
upper incisor is relatively small. In _S. hoyi_ (separated by some
writers as _Microsorex_), of the same country, this tooth is rudimentary.
Other North American Shrews, which are regarded by some zoologists as
generically distinct under the name of _Neosorex_, are aquatic, and
thus take the place of the Old World genus _Crossopus_. These are _S.
palustris_ of the Rocky Mountains and _S. hydrodromus_ of Unalaska
Island, both of which resemble _Crossopus_ in having the feet provided
with swimming fringes, but agree with the other species of _Sorex_ in
their dentition and the character of the tail. The former species is
about the size of _Crossopus fodiens_, while the latter is scarcely
larger than _S. pygmæus_.
_Soriculus._[543]—Dentition: _i_ ⁴⁄₂, _c_ ¹⁄₀, _p_ ¹⁻²⁄₁, _m_ ³⁄₃; total
30, or rarely 32. Opening of male or female generative organs forming
with the anal orifice a shallow cloaca. Ear and tail as in _Sorex_. First
upper incisor with an internal cusp. Habits terrestrial.
This genus is the only representative in the Oriental region of the
_Soricinæ_, which are otherwise confined to the Palæarctic and Nearctic
regions. The Indian and Burmese species comprise _S. nigrescens_, _S.
caudatus_, and _S. macrurus_.
_Notiosorex._[544]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃; total
28. Tail moderate; first upper incisor without an inner cusp; other
characters as in _Soriculus_. Habits terrestrial.
This American genus is represented by _S. crawfordi_ and _S. evotis_,
which are found in Central America and Mexico, and are thus some of the
most southerly representatives of the Shrews in that continent. Their
external appearance is very similar to that of the Old World genus
_Crocidura_.
_Blarina._[545]—Dentition: _i_ ⁴⁻³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total
32 or 30. Ear truncated above; tail short; otherwise as in _Soriculus_.
This group of so-called Earless or Short-tailed Shrews is mainly North
American, the common forms being _B. dekayi_ and _B. brevicauda_. The
species vary considerably in size; and _B. mexicana_ and _micrura_ extend
the range of the genus into Mexico and Guatemala. The following account
of the habits of _B. brevicauda_ is taken from Dr. Merriam’s _Mammals
of the Adirondack Region_: “The rigours of our northern winters seem to
have no effect in diminishing its activity, for it scampers about on the
snow during the severest weather, and I have known it to be out when the
thermometer indicated a temperature of -20° Fahr. It makes long journeys
over the snow, burrowing down whenever it comes to an elevation that
denotes the presence of a log or stump, and I am inclined to believe that
at this season it must feed largely upon the chrysalides and larvæ of
insects that are always to be found in such places.” Dr. Merriam has made
the interesting discovery that the common short-tailed North American
Shrew supplements its insectivorous fare by feeding on beech-nuts, which
will account for the generally very worn state of the teeth in this
species.
_Crossopus._[546]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁, _m_ ³⁄₃; total
30. Opening of male or female generative organs enclosed within the same
ring as the anal orifice; penis broad, with lateral processes. Ears
small, not truncated. Tail long, with an inferior fringe of elongated
hair; feet also fringed. Habits aquatic. The Palæarctic Water-Shrew (_C.
fodiens_) is considerably larger than the Common Shrew, from which it is
readily distinguished externally by its shorter and much broader muzzle,
comparatively smaller eyes, and larger feet adapted for swimming,—the
sides of the feet and toes being provided with comb-like fringes of stiff
hairs. The tail is longer than the body, and possesses a well-developed
swimming fringe of moderately long, regularly arranged hairs, which
extend along the middle of the flat under surface from the end of its
basal third to its extremity. The fur of the body is long and very dense,
varying much in colour in different individuals, and this has given rise
to descriptions of many nominal species; the prevailing shades are dark
brown, almost black, above, and more or less bright ashy tinged with
yellowish beneath; sometimes in the same litter there are individuals
with the under surface more or less dark coloured. In the number as well
as in the shape of the teeth the Water-Shrew differs from the Common
Shrew: there is a premolar less on each side above; the bases of the
teeth are much more prolonged posteriorly; and their cusps are much less
stained brown, so that in old individuals with worn teeth they often
appear altogether white. This species resembles the otter in its aquatic
habits, swimming and diving with great agility. It frequents rivers and
lakes, making its burrows in the overhanging banks, from which when
disturbed it escapes into the water. Its food consists of insects and
their larvæ, small crustaceans, and probably the fry of small fishes. It
is generally distributed throughout England, is less common in Scotland,
and as yet it has not been recorded in Ireland; specimens have been
obtained from many parts of Europe, and also from Asia as far eastward as
the Altai Mountains.
Subfamily =Crocidurinæ=.—Teeth completely white.
_Myosorex._[547]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁄₁₋₂, _m_ ³⁄₃; total
30 or 32. Penis cylindroid and tapering; male or female generative
organs opening close to anal orifice, but not forming a cloaca. Ears
well developed; tail long, clothed with equal or subequal hairs. Habits
terrestrial.
This genus is typically represented by _M. varius_, a very small Shrew
from the Cape, which is quite unique among the whole family in having a
rudimental seventh pair of lower teeth.
_Crocidura._[548]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ²⁻¹⁄₁, _m_ ³⁄₃; total
28 or 30. Male or female generative organs forming a short cloaca with
the anal orifice. Tail long, with a mixture of long and short hairs.
Other characters as in _Myosorex_. Habits terrestrial.
This Old World genus includes over seventy nominal species, which have
been divided into four subgenera, _C. aranea_ and _C. suaveolens_ of
Continental Europe, and _C. cœrulea_ of India, being well-known forms.
The species are very variable and difficult to discriminate. _C. aranea_
has a very wide distribution, ranging from Central and Southern Europe
to North Africa and Central Asia. The name Musk-Rat is popularly applied
in India to _C. cœrulea_, which frequents houses at night, hunting round
rooms for cockroaches and other insects, and occasionally uttering a
sharp shrill cry. The strong musky odour of this animal arises from
large glands situated beneath the skin of the side of the body, a short
distance behind the fore limbs. This odour is so powerful and penetrating
that it is popularly believed in India that if the animal runs over a
corked bottle of wine or beer it will infect the fluid within. Jerdon
says that certainly many bottles are met with quite undrinkable from the
peculiar musky odour of their contents, but, rejecting the possibility of
its passing through the glass, he attributes it to the corks having been
infected previously to bottling, stating in corroboration of this view
that he has never found the odour in liquors bottled in England.
_Diplomesodon._[549]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 26. Tail moderate; soles of the feet hairy. Other characters as in
_Crocidura_. Habits terrestrial.
This genus is represented only by _D. pulchellus_ of the Kirghiz steppes,
which is allied to the following form, although retaining the normal
Shrew-like external contour.
_Anurosorex._[550]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃; total
26. Ear very short; tail rudimental or short; soles of feet naked. Other
characters as in _Diplomesodon_.
The two species of this genus are Mole-like terrestrial forms, of which
the typical _A. squamipes_ occurs in Tibet, while _A. assamensis_ is
found in Assam. The latter species has the longer tail. The habits of
both are probably fossorial.
_Chimarrogale._[551]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 28. Penis broad, with lateral processes; male or female generative
organs opening within the same integumentary ring as the anal orifice.
Tail long, with an inferior fringe of elongated hairs; ears small;
plantar callosities simple; toes free. Habits aquatic.
This genus includes _C. himalayica_ of the Himalaya and _C.
platycephalus_ of Japan. Both have the feet fringed, and, together with
the next genus, may be regarded as the eastern analogues of _Crossopus_
among the red-toothed series; their structural resemblances to the
latter, if Dr. Dobson’s classification is a natural one, being probably
due to adaptation for a similar mode of life.
_Nectogale._[552]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ¹⁄₁, _m_ ³⁄₃;
total 28. External ears not forming a conch, valvular. Plantar
callosities forming adhesive pads; toes webbed. Other characters as in
_Chimarrogale_. Habits aquatic.
[Illustration: FIG. 288.—_Nectogale elegans._ (From Milne-Edwards,
_Mammif. Tibet_.)]
The sole representative of this genus is the Tibetan Water-Shrew (_N.
elegans_, Fig. 288), which differs from all other members of the family
by the webbed toes and the presence of the disc-like adhesive pads on the
under surface of the feet, which are believed to enable the creature to
hold on to smooth rocks or stones in the beds of the streams it inhabits.
This species is probably more completely aquatic in its habits than the
allied _Chimarrogale_.
_Fossil Soricidæ._—Remains of existing species of _Sorex_ or _Crossopus_
occur in the Norfolk Forest bed, while an extinct species has been found
in the Pleistocene of Sardinia. _Crocidura_ occurs in the cavern-deposits
of Madras. Shrews from the Miocene and Upper Eocene of Europe have been
referred to _Sorex_ and the genus _Amphisorex_, which is a synonym of
_Crossopus_.
_Family_ TALPIDÆ.
Allied to the _Soricidæ_, but distinguished by the presence of a
zygomatic arch and auditory bulla in the skull, and by the form of
the teeth. The eyes are very small, and in some species covered with
skin; the ears are short and concealed by the fur; the fore limbs are
generally more or less modified for digging; there is no symphysis pubis;
the intestine has no cæcum; the tibia and fibula are united; and the
unicuspidate first upper and lower incisors are not extended horizontally
forwards.
This family is connected with the _Soricidæ_ by _Urotrichus_ and
_Uropsilus_. All the members are limited to the temperate regions
of Europe, Asia, and North America; and the majority of them are of
fossorial habits, although a few are aquatic or cursorial. The family has
been divided into two subfamilies by Professor Mivart, and since this
arrangement has been very generally adopted it will be followed here.
From the presence of intermediate forms like _Scaptonyx_ Dr. Dobson, in
the second part of his _Monograph of the Insectivora_, has proposed a
different arrangement, which, with the omission of some forms which are
of not more than subgeneric value, is as follows:—
MYOGALÆ—_Myogale_.
CONDYLURÆ—_Condylura_.
SCALOPES { _Scapanus_.
{ _Scalops_.
TALPÆ—_Talpa_.
UROTRICHI { _Scaptonyx_.
{ _Urotrichus_.
UROPSILI—_Uropsilus_.
Subfamily =Myogalinæ=.—Clavicles and humerus moderately elongated; manus
without falciform bone.
_Myogale_.[553]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
44. Feet webbed. Habits aquatic. This genus is represented by the two
species _M. moschata_ (Fig. 289) and _M. pyrenaica_, of which the former
is by far the largest member of the family, its total length being about
16 inches. Its long proboscis-like snout projects far beyond the margin
of the upper lip; the toes are webbed as far as the bases of the claws;
and the long scaly tail is laterally flattened, so as to form a powerful
instrument of propulsion when swimming. This species inhabits the banks
of streams and lakes in South-East Russia, where its food consists of
various aquatic insects. _M. pyrenaica_, living in a similar manner in
the region of the Pyrenees, is very much smaller, has a round tail, and
a proportionally longer snout. Fossil remains of _M. moschata_ occur in
the Norfolk Forest bed, and were originally described under the name of
_Palæospalax_. The genus is also represented in the Middle and Lower
Miocene of the Continent.
[Illustration: FIG. 289.—The Desman (_Myogale moschata_). ¹⁄₃ natural
size.]
_Urotrichus._[554]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ⁴⁄₃ or ³⁄₄, _m_
³⁄₃; total 36. Feet not webbed; manus broad. Habits fossorial. The
Mole-Shrews, as these animals are called, are represented by _U.
talpoides_ of the mountains of Japan and _U. gibbsi_ of North America.
These two species are small and closely allied animals; the American form
(which it has been proposed to separate subgenerically as _Neurotrichus_)
having _p_ ³⁄₄.
_Uropsilus._[555]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
34. Manus narrow; tail naked and scaly. Habits cursorial. The single
species, _U. soricipes_, from the borders of Tibet, is a slate-coloured
animal with the external form of a Shrew but the skull of a Mole.
Subfamily =Talpinæ=.—Clavicle and humerus very short and broad; manus
with a large falciform bone.
A. First upper incisor much larger than the second (New World Moles).
_Scalops._[556]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₀, _p_ ³⁄₃, _m_ ³⁄₃; total
36. Extremity of muzzle simple; hind feet webbed; tail short and nearly
naked. Represented by three species in the United States.
_Scapanus._[557]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
44. Extremity of muzzle simple. The two North American species of this
genus resemble _Scalops_ in general characters, but have a dentition like
_Condylura_. The habits are like those of the latter, and the right to
generic distinction is doubtful.
_Condylura._[558]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃;
total 44. Extremity of muzzle surrounded by filiform appendages. The
Star-nosed Mole (_C. cristata_) derives its name from the star-like ring
of appendages at the extremity of the muzzle, with the nostrils in the
centre. The general contour is Mole-like, but the tail is nearly as long
as the body, and the manus is somewhat less powerful, with its terminal
phalanges not cleft. The length of the head and body is about 5 inches.
This species is common in parts of North America, and forms tunnels in
the ground like the Common Mole.
B. First upper incisor scarcely larger than the second (Old World Moles).
_Scaptonyx._[559]—Dentition: _i_ ³⁄₂, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; total
42. Manus moderately broad, as in _Urotrichus_. Represented only by _S.
fusicaudatus_ of Eastern Tibet, which may be regarded as connecting
_Talpa_ with _Urotrichus_, having the head of the former and the limbs of
the latter.
_Talpa._[560]—Dentition (usually): _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃;
total 44. Manus extremely broad.
This genus includes the true Moles, of which the common English
Mole[561] (_T. europæa_) is the type. This animal is about 6 inches in
total length, of which rather more than one inch is occupied by the
tail. The body is elongated and cylindrical, and, owing to the very
anterior position of the fore limbs, the head appears to rest between
the shoulders; the muzzle is long and obtusely pointed, terminated by
the nostrils, which are close together; the minute eye is almost hidden
by the fur; the ear is without a conch, and opens on a level with the
surrounding integument. The fore limbs are rather short and very
muscular, terminating in broad, naked, shovel-shaped feet, with the palms
normally directed outwards, and each with five subequal digits armed with
strong flattened claws. The hind feet are long and narrow, and the toes
are provided with slender claws. The body is densely covered with soft,
erect, velvety fur, the hairs being uniform in length and thickness,
except on the muzzle and short tail. The colour of the fur is generally
black, with a more or less grayish tinge, or brownish-black, but various
paler shades up to pure white have been observed.
The food of the Mole consists chiefly of the earth-worm, in pursuit of
which it forms its well-known underground excavations. Its habits were
many years ago studied and described by M. Henri le Court. Like many
other mammals, the Mole has a lair to which it may retire for security.
This consists of a central nest formed under a hillock, placed in some
protected situation, as under a bank, or between the roots of trees. The
nest, which is lined with dried grass or leaves, communicates with the
main run by four passages, of which only one joins it directly, leading
downwards for a short distance and then ascending again. The other
three are directed upwards and communicate at regular intervals with a
circular gallery constructed in the upper part of the hillock, which in
turn communicates by five passages leading downwards and outwards with
another much larger gallery placed lower down on a level with the central
nest, from which passages proceed outwards in different directions, one
only communicating directly with the main run, while the others, curving
round, either soon join or end blindly. The main run is somewhat wider
than the animal’s body: its walls are smooth, and formed of closely
compressed earth, the depth varying according to the nature of the soil,
but ordinarily from 4 to 6 inches. Along this tunnel the animal passes
backwards and forwards several times daily, and here traps are laid by
mole-catchers for its capture. From the main run numerous passages are
formed on each side, along which the animal hunts its prey, throwing out
the soil in the form of mole-hills. The Mole is one of the most voracious
of mammals, and, if deprived of food, is said to die in from ten to
twelve hours. Almost any kind of flesh is eagerly devoured by captive
Moles, which have been seen by various observers, as if maddened by
hunger, to attack animals nearly as large as themselves, such as birds,
lizards, frogs, and even snakes; toads, however, they will not touch, and
no form of vegetable food attracts their notice. If two Moles be confined
together without food, the weaker is invariably devoured by the stronger.
Moles take readily to the water, in which respect they resemble their
representatives on the North American continent. Bruce, writing in 1793,
remarks that he saw a Mole paddling towards a small island in the Loch of
Clunie, 180 yards from land, on which he noticed mole-hills.
The sexes come together about the second week in March, and the
young—generally from four to six in number—which are brought forth in
about six weeks, quickly attain their full size.
[Illustration: FIG. 290.—Skeleton of Mole × ⅔ (lower jaw removed to
show base of skull). _c_, Calcaneum; _c.h._, clavicular articulation
of the humerus; _cl._, clavicle; _e.c_, external condyle of humerus;
_f._, femur; _fb_, fibula; _fc_, falciform bone (radial sesamoid); _h_,
humerus; _i.c_, internal condyle of humerus; _il_, left ilium; _i.p_,
ramus of the ilium and pubis; _is._, ischium; _l.d_, ridge of insertion
of latissimus dorsi muscle; _l.t_, lesser trochanter; _m_, manubrium
sterni; _o_, fourth intercentral ossicle; _ol_, olecranon; _p._, pubis
widely separated from that of the opposite side; _pa._, patella; _p.m._,
ridge for insertion of pectoralis major muscle; _pt._, pectineal
eminence; _r_, radius; _rb_, first rib; _s_, plantar sesamoid ossicle
corresponding to the radial sesamoid (os falciforme) in the manus; _sc._,
scapula; _s.h._, scapular articulation of the humerus; _t_, tibia; _u_,
ulna.]
The Mole exhibits in the whole of its organisation a perfect adaptation
to its peculiar mode of life. In the structure of the skeleton (Fig.
290) very striking departures from the typical mammalian form are
noticeable. Thus the presternum is so much produced anteriorly as to
extend forward as far as a vertical line from the second cervical
vertebra, carrying with it the very short and almost quadrate clavicle,
which is articulated with its anterior extremity and distally with the
humerus; being also connected ligamentously with the scapula. The fore
limbs are thus brought opposite the sides of the neck, and from this
position a threefold advantage is derived: in the first place, as this
is the narrowest part of the body, they add but little to the general
width, which if increased, would lessen the power of movement in a
confined space; secondly, this position allows of a longer fore limb than
would otherwise be possible, and so increases its power; and, thirdly,
although the entire limb is relatively very short, its anterior position
enables the animal, when burrowing, to thrust the claws so far forward
as to be in a line with the end of the muzzle, the importance of which
is evident. Posteriorly, the hind limbs are similarly removed out of the
way by approximation of the hip-joints to the centre line of the body.
This is effected by inward curvature of the innominate bones at the
acetabula to such an extent that they almost meet in the centre, while
the pubic bones are widely separated behind. The shortness of the fore
limb is caused by the great reduction in the length of the humerus, which
has lost all resemblance to its normal shape. In addition to the usual
articulation with the glenoid cavity of the scapula, the humerus also has
a separate articulation with the extremity of the clavicle. The bones
of the manus are enormously expanded laterally; this expansion being
increased by the large sickle-like bone on the radial side of the carpus,
which is considered by some anatomists to represent the prepollex. The
skull is long and tapering, with very slender zygomatic arches and
elongated nasals, which are ankylosed together, and in advance of which
the mesethmoid is more or less ossified. The vertebræ are usually C 7,
D 13, L 6, S 6, C 10-12; all having very strong surfaces for mutual
articulation. The upper incisors are chisel-like, and the canine has two
roots; the first three upper premolars are simple and conical, but the
fourth is much larger, and canine-like. In the mandible the incisors are
small and somewhat proclivous, while the canine can only be distinguished
from them by its position: the first lower premolar is larger than the
others.
The Common Mole has an exceedingly wide distribution, ranging over the
greater part of the Palæarctic region, where it is met with in places so
widely sundered as England and Japan. It occurs in both the Himalaya and
Altai mountains. In Ireland it is unknown, and in Scotland it extends as
far north as Caithness. Eight species of the genus are recognised, which
may be grouped, from the characters of their dentition, as follows, viz.:
_i_ ³⁄₃, _c_ ¹⁄₀, _p_ ⁴⁄₄, _m_ ³⁄₃, _T. wogura_; _i_ ³⁄₃, _c_ ¹⁄₁, _p_
⁴⁄₄, _m_ ³⁄₃, _T. europæa_, _cæca_, _longirostris_, _micrura_; _i_ ³⁄₃,
_c_ ¹⁄₁, _p_ ³⁄₄, _m_ ³⁄₃, _T. leucura_, _leptura_; _i_ ³⁄₃, _c_ ¹⁄₁, _p_
³⁄₃, _m_ ³⁄₃, _T. moschata_.
Except in _T. europæa_, the eyes are covered by a membrane. In _T.
micrura_ the short tail is concealed by the fur. _T. cæca_ is found south
of the Alps; the remaining species are Asiatic, and two only—_T. micrura_
and _T. leucura_—occur south of the Himalaya. _T. moschata_, of Tibet,
is regarded by some zoologists as generically distinct under the name of
_Scaptochirus_.
Remains of _T. europæa_ occur in the Norfolk Forest bed, while extinct
species are found in the European Tertiaries as far down as the Lower
Miocene, although it has been proposed to separate some of these forms
generically. _Protalpa_, of the Upper Eocene Phosphorites of Central
France, is very closely allied, but the structure of the humerus is
somewhat less specialised.
_Extinct Genera._—A number of extinct Insectivora from the European
Tertiaries more or less closely allied to the Moles have been described,
but since our knowledge of most of them is extremely imperfect their
precise affinities are in many instances problematical. Of these, the
Lower Miocene _Tetracus_ is said to have affinity both with _Myogale_ and
_Erinaceus_; while the forms described as _Mysarachne_ and _Echinogale_,
are considered to connect the present with the two preceding families.
_Plesiosorex_ is another Lower Miocene type known only by the mandible,
in which there are ten teeth; it is generally referred to the
_Myogalinæ_. The minute _Amphidozotherium_, of the French Phosphorites,
is considered to be allied to _Urotrichus_.
_Family_ ADAPISORICIDÆ.
This extinct family is represented by the genera _Adapisorex_ and
_Adapisoriculus_, of the lowest Eocene of Rheims, which are regarded as
allied to the _Soricidæ_, but somewhat more specialised. In the type
genus the formula of the lower teeth is _i_ 2, _c_ 1, _p_ 4, _m_ 3; the
incisors and canine being proclivous, and the molars (of which the last
is small and without a third lobe) quadritubercular. _Adapisoriculus_ is
a smaller form with differently shaped molars.
[Illustration: FIG. 291.—The last left upper cheek-teeth of
_Pleuraspidotherium aumonieri_; from the Lowest Eocene of Rheims. _pr_,
protocone; _me_, metacone; _pa_, paracone; _b_, cingulum-cusp. (From
Osborn.)]
Here also may be mentioned the genera _Orthaspidotherium_ and
_Pleuraspidotherium_, from the above-mentioned deposits, which are
probably members of the present order. They appear to have been animals
somewhat smaller than a Hedgehog, with quadritubercular upper molars
(Fig. 291), and the hinder premolars more complex than those of the
_Erinaceidæ_. In the first-named genus the dental formula is _i_ ³⁄₃, _c_
¹⁄₁, _p_ ⁴⁄₄, _m_ ³⁄₃; the third and fourth upper premolars having one
outer column. _Pleuraspidotherium_ has apparently only three premolars,
of which the third and fourth (Fig. 291) have two outer columns. The
humerus in both has no entepicondylar foramen, the femur has a third
trochanter, and the astragalus is vertically perforated.
_Family_ POTAMOGALIDÆ.
Skull with a small brain-case, no zygomatic arch or postorbital process,
and the tympanic annulate and not forming a bulla. Upper molars with the
cusps arranged in a broad V, and somewhat intermediate in structure
between those of the preceding and succeeding families. No clavicle;
pubic symphysis ligamentous; tibia and fibula typically united distally.
No cæcum. Confined to the Ethiopian region.
[Illustration: FIG. 292.—_Potamogale velox._ × ¼. (From Allman, _Trans.
Zool. Soc._ vol. vi. pl. i.)]
_Potamogale._[562]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. Represented only by _P. velox_ of Western Equatorial Africa. This
animal (Fig. 292) inhabits the banks of streams, and is thoroughly
adapted for an aquatic life; it is nearly 2 feet in length, the
tail measuring about half. The long cylindrical body is continued
uninterruptedly into the thick laterally compressed tail, the legs are
very short, and the toes are not webbed, progression through the water
evidently depending wholly on the action of the powerful tail, while the
limbs are folded inwards and backwards. The muzzle is broad and flat, and
the nostrils are protected by valves. The fur is dark brown above, the
extremities of the hairs on the back being of a metallic violet hue by
reflected light, beneath whitish. This curious animal was discovered by
M. du Chaillu.
_Geogale._[563]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₂, _m_ ³⁄₃; total 34.
This genus is known solely by _G. aurita_, a small Mouse-like species
from Madagascar, agreeing closely with _Potamogale_ in the general form
of the skull and teeth. The tibia and fibula are distinct, but it is not
known whether a clavicle exists; and the material at present available is
insufficient to definitely fix the natural position of the genus.
_Family_ SOLENODONTIDÆ.
Skull with a small brain-case constricted between the orbits, no
zygomatic arch or postorbital process, and the tympanic annulated and not
forming a bulla. Upper molars tritubercular, the cusps being arranged in
a V. Pubic symphysis short; tibia and fibula distinct. Vertebræ: C 7, D
15, L 4, S 5, C 23. No cæcum. The penis is carried forwards and suspended
from the abdomen; the testes are received into perineal pouches; the
mammary glands are post-inguinal; the uterine cornua end in cæcal sacs.
[Illustration: FIG. 293.—_Solenodon cubanus._ × ⅕ (From Peters, _Abh.
Akad. Berlin_.)]
_Solenodon._[564]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus, with _S. paradoxus_ and _S. cubanus_ (Fig. 293), from
Hayti and Cuba respectively, alone represents the family. These species,
which differ chiefly in the colour and quality of the fur, have a
remarkably long cylindrical snout, a long naked tail, feet formed for
running, and the body clothed with long, coarse fur.
The position of the mammæ quite behind on the buttocks is unique among
Insectivora. The first upper incisor is much enlarged, and this and
the other incisors, canines, and premolars, closely resemble those of
_Myogale_; the second lower incisor is, as in _Potamogale_, much larger
than the anterior one, and is deeply hollowed out internally. While thus
apparently showing relationship with the _Talpidæ_, the form of the
crowns of the molar teeth connects them with the next family.
_Family_ CENTETIDÆ.
Skull (Fig. 294) with a small cylindrical brain-case not constricted
between the orbits, no zygomatic arch or postorbital process, and the
tympanic annulate and not forming a bulla. Upper molars tritubercular.
Pubic symphysis short; and the tibia and fibula either united or free.
No cæcum. The penis is pendent and retractile within the fold of the
integument surrounding the anus; the testes are abdominal; the mammæ
are thoracic and ventral; and the uterine cornua are terminated by the
Fallopian tubes. All the species are limited to Madagascar.
[Illustration: FIG. 294.—Left lateral view of the skull of the Tenrec
(_Centetes ecaudatus_). Reduced.]
Subfamily =Centetinæ=.—Tibia and fibula distinct; testes near kidneys;
fur with spines.
_Centetes._[565]—Dentition: _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 38.
Vertebræ: C 7, D 19, L 5, S 3, C 8. The single species is the well-known
Tenrec (_C. ecaudatus_), characterised by the absence of a tail; it
reaches a total length of from 12 to 16 inches, and is the largest known
Insectivore. The adult males have long canines, the extremities of the
lower pair being received into pits in front of the upper ones (Fig.
294). It is probably the most prolific of all mammals, since as many as
twenty-one young are said to have been brought forth at a birth. The
young have strong white spines arranged in longitudinal lines along the
back, but these are lost in the adult animal, which is provided only with
a nuchal crest of long rigid hairs. In rare instances a fourth upper
molar may be developed.
_Hemicentetes._[566]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus is represented by the two species _H. semispinosus_ (of
which the skull is shown in Fig. 295) and _H. nigriceps_. It differs from
_Centetes_ by the presence of the third upper incisor, the much smaller
canines, and by the form of the skull. Both species are very much
smaller than _C. ecaudatus_, and the dorsal spines are retained in the
adult state. Vertebræ: C 7, D 16, L 5, S 3, C 9.
_Ericulus._[567]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 36.
Vertebræ: C 7, D 17, L 6, S 4, C 9. The single species, _E. setosus_,
is a Hedgehog-like animal, having the whole upper surface and the short
tail densely covered with close-set spines. The facial bones are much
shorter than in any of the preceding genera, and the first upper incisor
is elongated, as in _Erinaceus_. Judging from the slight development of
the cutaneous muscles compared with those of the true Hedgehogs, it is
probable that complete involution of the body does not take place.
Subfamily =Oryzorictinæ=.—Tibia and fibula united; testes near urethra;
fur without spines.
[Illustration: FIG. 295.—Skull of _Hemicentetes semispinosus_. × 2. (From
Mivart, _Proc. Zool. Soc._ 1871.)]
_Microgale._[568]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total
40. This genus includes _M. longicaudata_ and _M. cowani_, both of which
are small Mouse-like species, the former with a tail double the length
of the head and body, and having 43 caudal vertebræ; teeth like those
of _Centetes ecaudatus_, but, owing to the comparatively much shorter
muzzle, not separated by wide spaces, and the last premolar and molar
with internal basal processes.
_Oryzorictes._[569]—Represented by two species, _O. hova_ and _O.
tetradactylus_, the latter distinguished by the presence of only four
digits in the manus, the three inner having long laterally compressed
fossorial claws. The general form of the head and body of the two species
known is like that of a Mole. These animals burrow in the rice-fields and
do much damage to the crops.
_Family_ CHRYSOCHLORIDÆ.
Skull conical, not constricted between the orbits, without postorbital
process, but with well-developed zygomatic arch and tympanic bulla. Upper
molars tritubercular, with the crowns very tall. No pubic symphysis; the
tibia and fibula united. The eyes are covered by the hairy integument;
the ears short and concealed by the fur; the internal generative organs
are as in _Centetinæ_; the mammæ are thoracic and inguinal and placed in
cup-shaped depressions. Habits fossorial. Confined to the southern part
of the Ethiopian region, not extending to Madagascar.
This family is closely allied to the _Centetidæ_, occupying the same
relative position with respect to that family that the _Talpidæ_ does
to the _Soricidæ_. Compared with the _Talpidæ_, we find the following
differences in the structural adaptation to a fossorial life; the
manubrium sterni is not anteriorly elongated, neither are the clavicles
shortened; but this is compensated for by a deep hollowing out of the
antero-lateral walls of the thorax, the ribs in these parts and the
sternum being convex inwards. The long clavicles have their distal
extremities pushed forward, and the concavities on the sides and inferior
surface of the thorax lodge the thick muscular arms.
[Illustration: FIG. 296.—The Golden Mole (_Chrysochloris obtusirostris_).]
_Chrysochloris._[570]—Dentition: _i_ ³⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁻²⁄₃₋₂;
total 40 or 36. Vertebræ: C 7, D 19, L 3, S 5, C 8. This genus includes
some seven or eight South African species, commonly known as Golden
Moles (Fig. 296). Those species, in which the molars are reduced to ²⁄₂,
with a basal talon to the lower ones, and without a prominence in the
temporal fossa, have been placed in a separate genus, _Chalcochloris_,
by Professor Mivart. Nearly all the species have the fur of the upper
surface of a brilliant metallic lustre, varying from golden bronze to
green and violet of different shades. The manus has four digits, of which
the two outer are small, while the middle ones are large, with immensely
powerful claws.
_Extinct Types._—The only fossil forms which can be referred to
the section of the Insectivora with tritubercular molars are the
_Leptictidæ_, of the Eocene and Miocene of North America. This family
includes the genera _Leptictis_, _Mesodectes_, and _Ictops_, all of which
are regarded by Dr. Schlosser as true Insectivora, although they were
placed by Professor Cope with the Creodont Carnivora.
_Bibliography of Insectivora._—Peters, _Reise nach
Mossambique—Säugeth._ 1852; Id. “Ueber die Classification
der Insectivora,” _Monatsb. Akad. Wissensch. Berlin_, 1865,
and other papers; Mivart, “On the Osteology of Insectivora,”
_Journ. Anat. and Phys._ 1867, 1868, and _Proc. Zool. Soc._
1871; Gill, “Synopsis of Insectivorous Mammals,” _Bull. Geol.
and Geog. Survey, U.S.A._ Washington, 1875 (includes a
general bibliography of the order); Dobson, _Monograph of the
Insectivora, Systematic and Anatomical_, London, 1882-90.
CHAPTER XIII
THE ORDER CHIROPTERA.
Mammals, having their fore limbs specially modified for flight. The
forearm consists of a rudimentary ulna, and a long curved radius.
The carpus has six bones supporting a small pollex and four greatly
elongated fingers, between which and the sides of the body and the
hinder extremities a thin expansion of the integument (the wing-membrane
or patagium) is extended. The knee is directed backwards, owing to the
rotation of the hind limb outwards by the wing membrane; a peculiar
elongated cartilaginous process (the calcar), rarely rudimentary or
absent, arising from the inner side of the ankle-joint, is directed
inwards, and supports part of the posterior margin of an accessory
membrane of flight, extending from the tail or posterior extremity of
the body to the hinder limbs (the interfemoral membrane). The penis
is pendent; the testes are abdominal or inguinal; the mammary glands
thoracic and generally postaxillary; the uterus is simple or with more or
less long cornua; the placenta discoidal and deciduate; and the smooth
cerebral hemispheres do not extend backwards over the cerebellum. The
dental series includes incisors, canines, premolars, and molars and never
exceeds _i_ ²⁄₃, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ³⁄₃; total 38.
The animals comprised in this order are at once distinguished by the
presence of true wings, and this peculiarity is accompanied by other
modifications of bodily structure having special relation to flight.
Thus, in contrast to most other mammals, in which the hind limbs greatly
preponderate in size over the fore, in the present order the fore limbs
immensely exceed the short and weak hinder extremities. The thorax, as
giving origin to the great muscles which sustain flight, and containing
the proportionately large lungs and heart, is remarkably capacious, and
the ribs are flattened and close together; the shoulder-girdle is also
greatly developed in comparison with the weak pelvic bones.
Linnæus included the Bats among the Primates, mainly on account of the
number of their upper incisors, supposed to be always four, the thoracic
position of the mammæ, and the pendent condition of the penis. Many
other zoologists, taking into consideration the placental characters and
the form of the uterus, have followed him; but it is evident that the
situation of the mammæ is related to the necessarily central position of
the young during flight, the shortness of the uterine cornua, observable
in so many species, to the generally uniparous gestation requiring less
room, while the discoidal deciduate placenta is equally present in and
characteristic of the Insectivora, many species of which also have the
penis pendent. Thus, the reasons for maintaining the Bats in this high
position being disposed of, we find in the low organisation of their
brain a proof of their inferior status; while furthermore, although they
differ widely from all other mammals in external form, it is evident that
this is only the result of special adaptation to aerial locomotion; and,
taking into account their whole bodily structure, we may accept the view
of Professor Huxley that they should merely be regarded as exceedingly
modified Insectivora.
So thoroughly, however, has this adaptation for flight been carried out
that of all animals the Bats are the least terrestrial, not one of them
being equally well fitted for progression on the earth. This is due to
the hind as well as the fore limbs being pressed into the service of
aerial locomotion. Thus the hind limb is so rotated outwards by the
wing-membrane that, contrary to what obtains in all other vertebrates,
the knee is directed backwards, and corresponds in position to its serial
homologue the elbow. It necessarily follows from this arrangement that
when a Bat is on the ground it rests on all fours, having the knees
directed upwards; while, in order to bring it into a position for forward
progression, the foot rotates forwards and inwards on the ankle. Walking
under these circumstances is at best only a kind of shuffle, and that
this is fully recognised by the animal is evidenced by its great anxiety
to take wing, or, if this be impracticable, to ascend to some point
where it can hitch itself up by the claws of the hind legs in its usual
position when at rest.
[Illustration: FIG. 297.—Skeleton and flying-membranes of the Noctule
Bat (_Vesperugo noctula_). × ⅓. _c_, Clavicle; _h_, humerus; _r_,
radius; _u_, ulna (rudimentary); _d¹_, pollex; _d²_, _d³_, _d⁴_, _d⁵_,
other digits of the manus supporting _wm_, the wing-membrane; _m_, _m_,
metacarpal bones; _ph¹_, first phalanx; _ph²_, second phalanx; _ph³_,
third phalanx; _am_, antebrachial membrane; _f_, femur; _t_, tibia; _fb_,
fibula (rudimentary); _c_, calcar supporting _im_, the interfemoral
membrane; _pcl_, postcalcaneal lobe.]
The bones of the skeleton are characterised by their slenderness and
the great size of the medullary canals in those of the extremities.
The vertebral column is short, and the vertebræ differ very slightly
in number and form throughout the species. The general number of the
dorso-lumbar vertebræ is 17, of which 12 are dorsal; the cervicals are
very broad, but short from before backwards, their breadth being due to
the great transverse diameter of the spinal canal rendered necessary by
the comparatively large size of the spinal cord, which, after giving off
the nerves to the fore limbs and thorax, rapidly diminishes in size,
and in the lumbo-sacral region is reduced to a fine thread. Except in
the frugivorous _Pteropodidæ_, the vertebræ, from the third cervical
backwards, are devoid of neural spines. From the first dorsal to the
last lumbar vertebra the spinal column forms a single curve backwards,
which is most pronounced in the lumbar region. The centra of the vertebræ
are but slightly movable upon each other, and in old individuals appear
to become partially ankylosed together. The caudal vertebræ are simple
cylindrical bones without processes; their number and length being
extremely variable even in closely allied species; and the anterior
caudals are generally united to the ischial tuberosities. The relative
development of the caudal vertebræ is, indeed, intimately correlated
to the habits of the animals; the long tail in the insectivorous forms
supporting and controlling the position of the large interfemoral
membrane, which appears not only to aid their rapid motions when in
pursuit of their prey by acting as a rudder, but also to assist in the
capture and retention of the larger insects. In the frugivorous types,
on the other hand, this is not required, and the tail is accordingly
rudimentary or absent. In all Bats the presternum has a prominent keel
for the attachment of the great pectoral muscles. In most species the
ribs are much flattened, and in some they are partially ankylosed by
their contiguous margins.
The skull is subject to considerable structural variations, even
within the limits of a single family. Postorbital processes to the
frontals are found only in the _Pteropodidæ_, and some _Nycteridæ_ and
_Emballonuridæ_. _Pteropus leucopterus_ and _Pteralopex_ are peculiar in
having the orbit completely surrounded by bone. A slender zygomatic arch
is present, except in some of the _Phyllostomatidæ_.
The milk-teeth are peculiar in that they are utterly unlike those of the
permanent series. They are slender, with sharp recurved cusps; and as a
rule are shed at an early period (in the _Rhinolophidæ_ before birth),
but may coexist with some of the fully developed permanent teeth. The
permanent teeth are subject to great variation of form, although they
always have distinct roots. In the Insectivorous types they are acutely
cusped, the cusps in those of the upper jaw being arranged in a more or
less distinct W; but in the frugivorous forms, like the _Pteropodidæ_ and
some of the _Phyllostomatidæ_, the molars are longitudinally grooved or
hollowed out.
The pectoral girdle maintains a very constant type. Thus the clavicle is
very long, strong, and curved; and the scapula large, oval, triangular,
with a long curved coracoid process. The humerus, though long, is
scarcely two-thirds the length of the radius. The ulna is rudimentary,
its proximal extremity, which articulates with but a small part of the
humerus, being ankylosed to the radius; and immediately beyond the joint
it is reduced to a slender splint-like bone, extending about as far
as the middle of the radius. In all species a detached sesamoid bone
exists in the tendon of the triceps muscle. The radius is very long,
in some species actually equal to the length of the head and body. The
proximal row of the carpus consists of a single bone formed by the united
scaphoid, lunar, and cuneiform; which, with the extremity of the radius,
forms the radio-carpal joint. In the distal row the trapezium, trapezoid,
and magnum vary in size in the different families, the unciform appearing
to be the most constant, and the pisiform being generally very small.
The manus is always furnished with five digits. The first, fourth, and
fifth digits consist of a metacarpal and two phalanges; but in the
second and third digits the number of phalanges is different in certain
families. The pollex always terminates in a claw, which—like the proximal
phalanx—is best developed in the frugivorous species. In most of the
frugivorous _Pteropodidæ_ the second digit is provided with a claw; but
in all other Bats this and the remaining digits are unarmed. In the
genus _Triænops_ alone a very peculiar short bony process projects from
the outer side of the proximal extremity of the terminal phalanx of the
fourth digit. The relative development of the digits and their phalanges
will be noticed under each family.
As might be expected from the small size of the posterior limbs, the
pelvic girdle is relatively weak. The ilia are long and narrow. In the
males of most species the pubic bones of opposite sides are very loosely
united in front, while in females they are widely separated; and in
the family _Rhinolophidæ_ alone do these bones form a symphysis. The
ileo-pectineal eminence develops a long pectineal process, which in the
subfamily _Hipposiderinæ_ is continued forwards to the anterior extremity
of the ilium enclosing a preacetabular foramen unique among mammals. The
acetabulum is small and directed outwards and slightly upwards; and with
this is related the peculiar position of the hind limb already noticed
as one of the chief characteristics of the order. The femur is slender
and cylindrical, with a small head and very short neck, and scarcely
differs in form throughout the order. The bones of the leg and foot are
variable; in the subfamily _Molossinæ_ alone is there a well-developed
fibula, while in all other species this bone is either very slender, or
cartilaginous and ligamentous in its upper third, or reduced to a small
bony process above the heel, as in _Megaderma_, or altogether absent, as
in _Nycteris_.
The foot consists of a very short tarsus, and of slender, laterally
compressed toes, with much curved claws. The hallux is composed of a
metacarpal, a proximal and an ungual phalanx, and is slightly shorter
than the other four toes, each of which has an additional phalanx, except
in the subfamily _Hipposiderinæ_ and in the anomalous genera _Thyroptera_
and _Myxopoda_, where all the toes have the same number of phalanges as
the first digit, and are equal to it in length. In the genus _Chiromeles_
the first digit is thumb-like and separated from the others, and in the
typical _Molossinæ_ the first and fifth digits are much thicker than the
intermediate toes.
The most noticeable peculiarities in the myology of the order consist in
the separated bands or slips into which the platysma is divided, and in
the presence of the remarkable muscle termed occipito-pollicalis, which
extends from the occipital bone to the base of the terminal phalanx of
the pollex.
Although, as already mentioned, the brain presents a low type of
organisation, yet probably no animals possess so delicate a sense of
touch as the Chiroptera. It is undoubtedly this perceptive power which
enabled the individuals deprived of sight, hearing, and smell, in
Spallanzani’s well-known experiments, to avoid the numerous threads hung
across the rooms in which they were permitted to fly about. In the
common Bats the tactile organs evidently exist, not only in the delicate
vibrissæ which spring from the sides of the muzzle, but also in the
highly sensitive and widely extended integumentary structures entering
into the formation of the wing-membranes and ear-conchs; while in many
other species, notably in the tropical Rhinolophine and Phyllostomatine
Bats, peculiar foliaceous cutaneous expansions surrounding the nasal
apertures or extending backwards behind them are added. These structures,
collectively known as the “nose-leaf” (whence the term “leaf-nosed
Bats”), have been shown by Dr. Dobson to be made up partly of the
extended and thickened marginal integument of the nostrils, and partly of
the highly differentiated glandular eminences occupying the sides of the
muzzle, in which, in all the common Bats, the vibrissæ are implanted.
In all species of leaf-nosed Bats, and especially in the _Rhinolophidæ_,
where the nasal appendages reach their highest development, the superior
maxillary division of the fifth nerve is of remarkably large calibre.
The nasal branch of this nerve, which is given off immediately beyond
the infraorbital foramen, is by far the largest portion; the palpebral
and labial branches consisting of a few slender nerve-fibres only. This
branch passes forwards and upwards on the side of the maxilla, but soon
spreads out into numerous filaments extending into the muscles and
integument above, and into the base of the nose-leaf. The nerve supply
of the nose-leaf is further augmented by the large nasal branch of the
ophthalmic division of the fifth nerve. While the many foliations,
elevations, and depressions which vary the form of the nose-leaf
greatly increase the sensory surface supplied by the fifth nerve, and
during rapid flight intensify the vibrations conveyed to it, the great
number of sweat and oil glands which enter into its structure perform
a function analogous to that of the glands of the auditory canal in
relation to the membrana tympani in maintaining its surface in a highly
sensitive condition. The nasal appendages of the Chiroptera may thus be
regarded as performing the office of an organ of a very exalted sense
of touch standing in the same relation to the nasal branches of the
fifth nerve as the aural apparatus to the auditory nerve; for, as the
latter organ collects and transmits the waves of sound, so the former
receives impressions arising from vibrations communicated to the air by
approaching objects.
In no order of mammals is the ear-conch so greatly developed or so
variable in form. Thus in most of the insectivorous species the ears
are longer than the head, while in some, as in the common Long-eared
Bat (_Plecotus auritus_), their length nearly equals that of the head
and body. The form of the conch is very characteristic of the various
families; in most the tragus is remarkably large, in some extending
nearly to the outer margin of the conch; and its function appears to be
to cause undulations in the waves of sound, and so intensify and prolong
them. It is worthy of notice that in the _Rhinolophidæ_, the only family
of insectivorous Bats wanting the tragus, the auditory bullæ reach their
greatest size, and the highly sensitive nasal appendages their highest
development; and that in the typical group of the _Molossinæ_ the
ear-conch is divided by a prominent keel; and the antitragus is unusually
large in those species in which the tragus is minute (see Fig. 298, _a_).
In the frugivorous Bats the form of the ear-conch is very simple, and but
slightly variable, throughout the various types.
[Illustration: FIG. 298.—Head of _Molossus glaucinus_. (From Dobson,
_Proc. Zool. Soc._ 1876.) _a_, Antitragus; _b_, keel of the ear-conch;
_c_, notch behind antitragus.]
In all Bats the ears are extremely mobile, each moving independently at
the will of the animal. This has been observed even in the frugivorous
_Pteropodidæ_, in which the peculiar vibratory movements first noticed in
_Artibeus perspicillatus_ may also be seen when the animals are alarmed.
The opening of the mouth is anterior in most species, but in many it is
inferior, the extremity of the nose being more or less produced beyond
the lower lip,—so much so indeed in the small South-American species
_Rhynchonycteris naso_ as to resemble that of the Shrews. The lips
exhibit the greatest variety in form, which will be referred to under
each family. The absence of a fringe of hairs is characteristic of all
fruit-eating Bats, and probably always distinguishes them from the
insectivorous species, which they may resemble in the form of their teeth
and other respects.
The œsophagus is narrow in all species, and especially so in the
sanguivorous Desmodont _Phyllostomatidæ_. The stomach presents two
principal types of structure, which correspond respectively to the two
great divisions of the order, the Megachiroptera and the Microchiroptera;
in the former (with the exception of _Harpyia_) the pyloric extremity
is more or less elongated and folded upon itself, in the latter it is
simple, as in the Insectivora Vera; a third exceptional type is met with
in the Desmodont _Phyllostomatidæ_, where the left or cardiac extremity
is greatly elongated, forming a long narrow cæcum-like appendage.
The intestine is comparatively short, varying from one and a half
to four times the length of the head and body, being longest in the
frugivorous and shortest in the insectivorous species. Only in _Rhinopoma
microphyllum_ and _Megaderma spasma_ has a very small cæcum been found.
The liver is characterised by the great size of the left lateral lobe,
which occasionally equals half the size of the whole organ; the right
and left lateral fissures are usually very deep; in the Megachiroptera
(_Harpyia_ excepted) the Spigelian lobe is ill-defined or absent, and
the caudate is generally very large; but in the Microchiroptera, on the
other hand, the Spigelian lobe is very large, while the caudate is small,
in most species forming a ridge only. The gall-bladder is generally
well developed and attached to the right central lobe, except in the
_Rhinolophidæ_, where it is connected with the left central.
In most species the hyoids are simple, consisting of a chain of
slender, elongated, cylindrical bones connecting the small basi-hyoid
with the cranium, while the pharynx is short, the larynx shallow with
feebly developed vocal cords, and guarded by a short, acutely-pointed
epiglottis, which in some genera (_Harpyia_, _Vampyrus_) is almost
obsolete. In _Epomophorus_, however, we find a remarkable departure
from the general type. Thus the pharynx is long and very capacious; the
aperture of the larynx is far removed from the fauces, and, opposite to
it, opens a canal, leading from the narial chambers, and extending along
the back of the pharynx; the laryngeal cavity is spacious and its walls
are ossified; the hyoid bone is quite unconnected, except by muscle, with
the cranium; the ceratohyals and epihyals are cartilaginous and greatly
expanded, entering into the formation of the walls of the pharynx, and in
the males of three species at least, supporting the orifices of a large
pair of air-sacs communicating with the pharynx (Fig. 299).
[Illustration: FIG. 299.—Head and neck of _Epomophorus franqueti_ (adult
male, natural size). The anterior (_a.ph.s_) and posterior (_p.ph.s_)
pharyngeal sacs are opened from without, the dotted lines indicating the
points where they communicate with the pharynx; _s_, thin membranous
septum in middle line between the anterior pharyngeal sacs of opposite
sides; _s.m._, sterno-mastoid muscle separating the anterior from the
posterior sac. (Dobson, _Proc. Zool. Soc._ 1881.)]
In extent, peculiar modifications, and sensitiveness the cutaneous
system reaches its highest development in this order. As a sensory organ
its chief modifications in connection with the external ear and with the
nasal and labial appendages have been described when referring to the
nervous system. It remains therefore to consider its relative development
as part of the organs of flight.
The extent and shape of the flying-membranes depend mainly on the form of
the bones of the anterior extremities, and on the presence or absence of
the tail. Certain modifications of these membranes, however, are met with
which do not depend on the skeleton, but are related to the habits of the
animals, and to the manner in which the wing is folded in repose.
These membranes consist of the “antebrachial membrane,” extending from
the point of the shoulder along the humerus and more or less of the
forearm to the base of the pollex, the metacarpal bone of which is
partially or wholly included in it; the “wing-membrane,” which is spread
out between the greatly elongated fingers, and extends along the sides
of the body to the posterior extremities, generally reaching to the
feet; and the “interfemoral membrane,” the most variable of all, which
is supported between the extremity of the body, the legs, and the calcar
(Fig. 297).
[Illustration: FIG. 300.—Frontal sac and nose-leaf in male and female of
_Hipposiderus larvatus_. (Dobson, _Proc. Zool. Soc._ 1873.)]
The antebrachial and wing-membranes are most developed in those species
fitted only for aerial locomotion, which when at rest hang with the body
enveloped in the wings; but in the family _Emballonuridæ_, and especially
in the subfamily _Molossinæ_ (the species of which are the best fitted
of all Bats for terrestrial progression), the antebrachial membrane is
reduced to the smallest size, and is not developed along the forearm,
leaving also the pollex quite free, and the wing-membrane is very
narrow and folded in repose completely under the forearm. The relative
development of the interfemoral membrane has been referred to above
in describing the caudal vertebræ. Its small size in the frugivorous
and sanguivorous species, in which its presence would be injurious as
impeding their motions when searching for food as they hang suspended
by their feet, is easily understood. Odoriferous glands and pouches
opening on the surface of the outer skin are developed in many species,
but in most cases more so in males than in females, and thus constitute
secondary sexual characters, which will be referred to when treating of
the peculiarities of certain species.
All the fossil Chiroptera at present known are true Bats in every sense
of the word, and therefore throw no light on the origin of the order.
The earliest representatives of the order occur in beds of Upper Eocene
(Lower Oligocene) age.
The order is divided by Dobson into the suborders Megachiroptera and
Microchiroptera.
_Suborder_ MEGACHIROPTERA.
Frugivorous Bats, generally of large size. Crowns of molars smooth,
marked with a longitudinal groove (cuspidate in _Pteralopex_); bony
palate continued behind the last molar, narrowing slowly backwards; three
phalanges in the index finger, the third phalanx generally terminated by
a claw; sides of the ear-conch forming a complete ring at the base; tail,
when present, inferior to (not contained in) the interfemoral membrane;
pyloric extremity of the stomach generally much elongated; the Spigelian
lobe of the liver ill-defined or absent, and the caudate well developed.
Limited to the tropical and subtropical parts of the eastern hemisphere.
Mr. O. Thomas[571] considers that the ordinary type of molar dentition
found in this suborder is a specialised adaptation from the cuspidate
type of the Microchiroptera; the genus _Pteralopex_ retaining the
ancestral form of teeth.
_Family_ PTEROPODIDÆ.
Since all the forms are included in this family its characters may be
taken to be the same as those of the suborder.
Subfamily =Pteropodinæ=.—Tongue moderate; molars well developed.
_Epomophorus._[572]—Dentition: _i_ ²⁻¹⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ¹⁄₂;
total 28 or 26. Tail absent or very short, when present free from
interfemoral membrane; second digit of manus clawed; premaxillæ united.
This genus includes some seven species inhabiting Africa south of the
Sahara. The head is large and long, and the lips are expansible, and
frequently with peculiar folds. The ears have a white tuft of hair on
the margin; and in the males of most species there are large glandular
pouches in the skin of the side of the neck near the shoulder, from the
mouth of which project long and coarse yellowish hairs, forming tufts
on the shoulders, from which the genus takes its name. Another male
secondary sexual character consists in the presence of a pair of large
air-sacs extending outwards on each side from the pharynx beneath the
integument of the neck, in the position shown in Fig. 299. These sacs
are evidently capable of being greatly distended at the will of the
animal, and their inflation probably occurs under the same circumstances
that the wattles of male gallinaceous birds swell up, namely, when
engaged in courting the females. Other remarkable conditions in which
these Bats appear to differ from all other species occur in the form of
the hyoid bones and larynx. These Bats appear to live principally on
figs, the juicy contents of which their large lips and capacious mouths
enable them to swallow without loss.
[Illustration: FIG. 301.—Head of Fox-Bat (_Pteropus personatus_). From
Gray, _Proc. Zool. Soc._ 1866.]
_Pteropus._[573]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃; total 34.
This genus has more than forty species, and thus includes more than half
the members of the family. All are of large size, and the absence of a
tail, the long pointed muzzle (Fig. 301), and the woolly fur covering the
neck render their recognition easy. They are commonly known as “Flying
Foxes,” or Fox-Bats; and one of the species (_P. edulis_) inhabiting Java
measures 5 feet across the fully extended wings, and is thus the largest
known species of the order. All the species closely resemble one another
in dentition, and are mainly distinguished by the form of the ears and
the quality of the fur. _P. scapulatus_, from North-East Australia,
approaches the species of the second subfamily in the remarkable
narrowness of its molars and premolars.
The range of this genus extends from Madagascar and the neighbouring
islands through the Seychelles to India, Ceylon, Burma, the Malay
Archipelago, Southern Japan, New Guinea, Australia, and Polynesia (except
the Sandwich Islands, Ellice’s Group, Gilbert’s Group, Tokelau, and the
Low Archipelago). Of the islands inhabited by it some are very small and
remote from any continent, such as Savage Island in the South Pacific and
Rodriguez in the Indian Ocean. Although two species inhabit the Comoro
Islands, which are scarcely 200 miles from the African coast, not a
single species is found in Africa; but in India, separated by thousands
of miles of almost unbroken ocean, a species exceedingly closely allied
to the common Madagascar Fox-Bat is abundant. The Malay Archipelago
and Australia are their headquarters; and in some places they occur in
countless multitudes. Mr. Macgillivray remarks of _P. conspicillatus_:
“On the wooded slope of a hill on Fitzroy Island I one day fell in with
this Bat in prodigious numbers, looking while flying in the bright
sunshine (so unusual for a nocturnal animal) like a large flock of rooks.
On close approach a strong musky odour became apparent, and a loud
incessant chattering was heard. Many of the branches were bending under
their load of Bats, some in a state of inactivity, suspended by their
hind claws, others scrambling along among the boughs, and taking to wing
when disturbed.”
[Illustration: FIG. 302.—Female and young of _Xantharpyia collaris_.
(From Sclater, _Proc. Zool. Soc._ 1870, p. 127.)]
_Xantharpyia._[574]—Dentition as in _Pteropus_, but a short tail present,
and the fur on the back of the neck similar to that of the body. This
genus is represented by some nine species, which have a distribution very
similar to that of _Pteropus_, except that they extend into Africa, and
are not found in Australia and Polynesia. _X. ægyptiaca_ inhabits the
chambers of the Great Pyramid and other deserted buildings in Egypt, and
is probably the species so generally figured in Egyptian frescoes. Fig.
302 exhibits an African species of this genus in the attitude assumed by
the Fox-Bats when at rest.
_Boneia._[575]—This genus, as represented by _B. bidens_ of Borneo,
differs from _Xantharpyia_ in having only a single pair of upper incisors.
_Cynopterus._[576]—Dentition: _i_ ²⁄₂₋₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₂; total
32 or 30. Muzzle short, grooved like _Pteropus_ in front; tail and fur
generally as in _Xantharpyia_, but the former sometimes wholly absent.
This genus, with seven species, is almost limited to the Oriental region.
_C. marginatus_ is very common in India, and extremely destructive to
ripe fruit of every description. Dr. Dobson states that “he gave to a
specimen of this Bat obtained at Calcutta a ripe banana, which, with the
skin removed, weighed exactly 2 ounces; the animal immediately, as if
famished with hunger, fell upon the fruit, seizing it between the thumbs
and the index fingers, and took large mouthfuls out of it, opening the
mouth to the fullest extent with extreme voracity. In the space of three
hours the whole fruit was consumed. Next morning the Bat was killed, and
found to weigh one ounce, or half the weight of the food eaten in three
hours. Indeed the animal when eating seemed to be a kind of living mill,
the food passing from it almost as fast as devoured, and apparently
unaltered, eating being, as it were, performed only for the pleasure of
eating.”
_Harpyia._[577]—Dentition: _i_ ¹⁄₀, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₂; total 24.
Premaxillæ well developed and united in front; facial bones much elevated
above the margin of the jaw, nostrils tubular (Fig. 303); body and
limbs as in _Cynopterus_. Includes two species from the Austro-Malayan
sub-region, readily recognised by the peculiar tubular and projecting
nostrils, as shown in the accompanying woodcut.
[Illustration: FIG. 303.—Head of _Harpyia major_. (From Dobson, _Proc.
Zool. Soc._ 1877.)]
_Cephalotes._[578]—Dentition: _i_ ¹⁄₁, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₃; total
28. Premaxillæ separate in front; nostrils simple; muzzle short; index
finger without a claw; tail short. Includes one species, having the same
distribution as _Harpyia_. The wing-membrane arises from the middle line
of the back, to which it is attached by a longitudinal very thin process
of the integument; the wings are quite naked, but the back covered by
them is clothed with hair.
_Pteralopex._[579]—External characters as in _Pteropus_; ears short
and hairy; wings arising from the middle line of the back. Muzzle very
short; plane of orbit directed more upwards than in _Pteropus_; orbit
surrounded by bone; sagittal crest strongly developed. Teeth cuspidate;
upper incisors with broad posterior ledges; upper canine short and thick,
with a stout secondary cusp in the middle of the posterior border, and
two smaller postero-internal basal cusps; cheek-teeth short and broad,
with their anterior and posterior basal ledges so developed and the main
cusps so nearly conical as to obliterate the longitudinal grooving of
_Pteropus_. Lower incisors very disproportionate, the outer pair being
nearly twenty times the bulk of the inner; lower canine stout, with a
simple posterior basal ledge. Represented by _P. atrata_ of the Solomon
Islands. As already mentioned, Mr. Thomas regards the dentition of this
genus as the most generalised type found in the suborder.
Subfamily =Carponycterinæ=.—Facial part of skull much produced; molars
narrow, and scarcely raised above the gum; and the tongue exceedingly
long, attenuated in the anterior third, and armed with long recurved
papillæ near the tip.
_Notopteris._[580]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ²⁄₂; total
28. Index finger without a claw; wings arising from the middle line of
the back; tail long; first upper premolar long, with two roots. The
single representative of the genus, _N. macdonaldi_, inhabits the Fiji
Islands, Aneiteum Island, and New Guinea. It is at once distinguished
from all other Bats of this family by the length of its tail, which is
nearly as long as the forearm.
_Eonycteris._[581]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃;
total 34. First upper premolar small, with a single root. This genus
is likewise represented by a single species (_E. spelæa_), from the
Farm Caves, Moulmein, Burma, which has somewhat the appearance of
_Xantharpyia_; but the absence of a claw to the index finger and the
characteristic tongue and teeth at once distinguish it.
_Carponycteris_[582] and _Melonycteris_,[583] each with a single
species, are closely allied; the index finger in both has a claw, and
the number of the teeth is the same as in _Eonycteris_. _Carponycteris
minima_ is the smallest known species of the suborder, being much smaller
than the common Noctule Bat of Europe, and its forearm scarcely longer
than that of the Long-eared Bat. It is nearly as common in certain
parts of India as _Cynopterus marginatus_ (compared with which it is
proportionally equally destructive to fruit), and extends eastward
through the Malay Archipelago as far as New Ireland, where it is
associated with _Melonycteris melanops_, distinguished from it by its
larger size and the total absence of the tail.
_Nesonycteris._[584]—Dentition: _i_ ²⁄₁, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃; total
32. Allied to _Melonycteris_, but distinguished by the absence of the
inner pair of lower incisors, and of a claw to the index finger. Tail
wanting. Represented by _N. woodfordi_, of the Solomon Islands.
_Callinycteris._[585]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ²⁄₂, _m_ ³⁄₃;
total 32. Allied to the preceding, but with a short tail; no claw to
index. One species from Celebes.
_Trygenycteris._[586]—Dentition: _i_ ²⁄₂, _c_ ¹⁄₁, _p_ ³⁄₃, _m_ ²⁄₃;
total 34. No external tail; a claw on index. One species from West Africa.
_Suborder_ MICROCHIROPTERA.
Insectivorous (rarely frugivorous or sanguivorous) Bats, of comparatively
small size. Crowns of molars acutely cusped, marked by transverse
grooves; bony palate narrowing abruptly, not continued backwards
laterally behind the last molar; one rudimentary phalanx (rarely two
phalanges or none) in the index finger, which is never terminated
by a claw; outer and inner sides of ear-conch commencing inferiorly
from separate points of origin; tail, when present, contained in the
interfemoral membrane, or appearing upon its upper surface; stomach
simple (except in the Desmodont _Phyllostomatidæ_); Spigelian lobe of the
liver very large, and the caudate generally small. Inhabit the tropical
and temperate regions of both hemispheres. The members of this suborder
may be divided into two sections.
_Section_ VESPERTILIONINA.
Tail contained within the interfemoral membrane; the middle pair of upper
incisors never large, and separated from each other by a more or less
wide space. Middle finger with two osseous phalanges only (except in
_Myxopoda aurita_, _Thyroptera tricolor_, and _Mystacops tuberculatus_).
First phalanx of the middle finger extended (in repose) in a line with
the metacarpal bone.
_Family_ RHINOLOPHIDÆ.
In all the species of this family the nasal appendages are highly
developed, and surround the sides of the nasal apertures, which are
situated in a depression on the upper surface of the muzzle; the ears are
large and generally separate, without trace of a tragus; the premaxillæ
are rudimentary, suspended from the nasal cartilages, and supporting
a pair of very small incisors; the molars have acute W-shaped cusps;
the skull is large, and the nasal bones which support the large nasal
cutaneous appendages are much expanded vertically and laterally; in
the females a pair of teat-like appendages are found in front of the
pubis; and the tail is long and produced to the posterior margin of the
interfemoral membrane. This family is found in the temperate and tropical
parts of the eastern hemisphere.
From whatever point of view the _Rhinolophidæ_ may be considered, they
are evidently the most highly organised of insectivorous Bats. In them
the osseous and cutaneous systems reach the most elaborate development.
Compared with those of the present family the bones of the extremities
and the flying-membranes of other Bats appear coarsely formed, and
even their teeth seem less perfectly fitted to crush the hard bodies
of insects. The very complicated nasal appendages, which evidently act
as delicate organs of special perception, here reach their highest
development, and the differences in their form afford valuable characters
in the discrimination of the species, which resemble one another very
closely in dentition and in the colour of the fur.
Subfamily =Rhinolophinæ=.—First toe with two, other toes with three,
phalanges each; ilio-pectineal spine not connected by bone with the
antero-inferior surface of the ilium.
[Illustration: FIG. 304.—Head of Indian Horse-shoe Bat (_Rhinolophus
mitratus_). (From Dobson, _Monogr. Asiat. Chiropt._)]
_Rhinolophus._[587]—Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ²⁄₃, _m_ ³⁄₃;
total 32. Nose-leaf (Fig. 304) with a central process behind and
between the nasal orifices, posterior extremity lanceolate, antitragus
large. Includes more than twenty species. _R. luctus_, in which the
forearm has a length of 3 inches, is the largest species, inhabiting
elevated hill tracts in India and Malayana; _R. hipposiderus_ of Europe,
extending into South England and Ireland, forearm 1·5 inches, is one
of the smallest; and _R. ferrum-equinum_, with the forearm 2·3 inches
in length, represents the average size of the species, which are
mainly distinguished from one another by the form of the nose-leaf.
The last-named species extends from England to Japan, and southward to
the Cape of Good Hope. The genus is represented in the Himalaya by the
closely allied _R. tragatus_, distinguished by having three vertical
grooves on the lower lip, in place of the single groove found in _R.
ferrum-equinum_. _Rhinolophus_ is represented in the Upper Eocene
Phosphorites of Central France by _R. antiquus_ and _R. dubius_; the
former appears to have the same dental formula as in the existing
species, but differs slightly in the structure of some of the lower
molars, so that it is separated generically by some writers under the
name of _Pseudorhinolophus_. The face is also longer than in existing
forms, and there are certain differences in the structure of the skull.
_Alastor_, from the same deposits, differs from _Rhinolophus_ by the
extreme shortness of the nasal region. _Palæonycteris_, from the Lower
Miocene of France, is said to be allied to _Rhinolophus_, but the
premolars are ³⁄₃, and the limb bones are stated to resemble those of
_Molossus_.
Subfamily =Hipposiderinæ=.—Toes equal, of two phalanges each;
ilio-pectineal spine united by a bony isthmus with a process derived from
the antero-inferior surface of the ilium.
[Illustration: FIG. 305. Head of _Hipposiderus calcaratus_. (From Dobson,
_Proc. Zool. Soc._ 1877.)]
_Hipposiderus._[588]—Dentition: _i_ ¹⁄₂, _c_ ¹⁄₁, _p_ ²⁻¹⁄₂, _m_ ³⁄₃;
total 30 or 28. Tail well developed. This genus, of which more than
twenty species have been described, differs from _Rhinolophus_ in the
form of the nose-leaf, which is not lanceolate behind and is unprovided
with a central process covering the nostrils. The largest species,
_H. armiger_, appears to be the most northerly, having been taken at
Amoy in China, and in the Himalaya at an elevation of 5,500 feet. Many
of the species are provided with a peculiar frontal sac behind the
nose-leaf, rudimentary in females (Fig. 305), which the animal can evert
at pleasure; the sides of this sac secrete a waxy substance, and its
extremity supports a pencil of straight hairs.
_Anthops._[589]—Like _Hipposiderus_, but with the tail rudimentary,
consisting merely of three or four vertebræ hidden in the base of the
interfemoral membrane. Nose-leaf very complicated, its upright transverse
portion emarginate above, and the projections rounded and hollowed
behind, and their substance quite thin. Premolars ²⁄₂. Represented by _A.
ornatus_ of the Solomon Islands.
Mr. O. Thomas, the describer of this Bat, remarks that it is evidently
more nearly allied to the preceding than to the succeeding genera,
although it agrees with _Cœlops_ in the rudimentary tail.
_Rhinonycteris_[590] and _Triænops_.[591]—These are two allied genera
with well-developed tails; the former being represented by _R. aurantia_
from Australia, and the latter by _T. persicus_ from Persia and Eastern
Africa. _Triænops_ (Fig. 306) is characterised by the remarkable form of
its nasal appendages and ears, and the presence of a peculiar osseous
projection from the proximal extremity of the second phalanx of the
fourth finger.
[Illustration: FIG. 306.—Head of _Triænops persicus_. × 2. (From Dobson,
_Monogr. Asiat. Chiropt._)]
_Cœlops._[592]—This genus is known only by a single species, _C. frithi_,
from the Bengal Sunderbans, Java, and Siam (in the roof of the great
pagoda at Laos); and is distinguished, not only by the form of its
nose-leaf, but also by the great length of the metacarpal of the index
finger, as well as by the shortness of the calcar and interfemoral
membrane and the rudimental tail.