Chapter IV: Latin Inscriptions (3)

The breast-bone, or sternum, is variable, but generally narrow, bilobate in front and divided into segments. The shoulder-girdle presents extreme adaptive modifications in the mole, in relation to the use of the fore-limbs in burrowing; but in the golden moles the fore-arm and fore-foot alone become specially modified. In _Macroscelides_ the bones of the fore-arm are united at their lower ends, but in all other Insectivora the radius and ulna are distinct. The fore-foot has generally five digits; but in _Rhynchocyon_ and in one species of _Oryzorictes_ the first toe is absent, and in the moles it is extremely modified. The femur has, in most species, a prominent ridge below the greater trochanter presenting the characters of a third trochanter. In _Tupaia_, _Centetes_, _Hemicentetes_, _Ericulus_ and _Solenodon_ the tibia and fibula are distinct, but in most other genera united. The hind-foot consists usually of five digits (rarely four by reduction of the first), and in some, as in the leaping species (Macroscelides, _Rhynchocyon_), the tarsal bones are elongated. The form of the pelvis, and especially of the symphysis pubis, varies within certain limits, so that while in the _Tupaiidae_ and _Macroscelididae_ there is a long symphysis, in the _Erinaceidae_, _Centetidae_ and _Potamogalidae_ it is short, and in the _Soricidae_, _Talpidae_ and _Chrysochloridae_ there is none.

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 the digestive organs. The stomach is a simple, thin-walled sac; sometimes as in _Centetes_, with the pyloric and oesophageal openings 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 _Tupaia_ and the allied _Macroscelididae_, which probably feed on vegetable substances as well as insects most of the species possess a caecum. The liver is deeply divided into lobes, the right and left lateral being cut off by deep fissures; both the caudate and Spigelian lobes are generally well developed, and the gall-bladder, usually large and globular, is placed on the middle of the posterior surface of the right central lobe.

All the members of the order appear to be highly prolific, the number of young varying from two to eight in the hedgehog, and from twelve to twenty-one in the tenrec. The position of the milk-glands and the number of teats vary greatly. In _Solenodon_ there is a single pair of post-inguinal teats, but in most species these organs range from the thorax to the abdomen, varying from two pairs in _Gymnura_ to twelve in the tenrec. In the golden moles the thoracic and inguinal teats are lodged in deep cut-shaped depressions.

Scent-glands exist in many species. In most shrews they occur on the sides of the body at a short distance behind the axilla, and their exudation is probably protective, as few carnivorous animals will eat their dead bodies. In both species of _Gymnura_ and in _Potamogale_ large pouches are situated on each 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 vent. In the tenrec similarly situated glands discharge by pores opening at the bottom of deep pits.

The skin is thin, but in many species lined with well-developed muscles, which are probably more developed in hedgehogs than in any other mammals. In this family and in the tenrec most of the species are protected by spines implanted in the skin-muscle, or panniculus carnosus.

Tree-Shrews.

The Insectivora may be divided into two groups, according to the
degree of development of the union between the two halves of the
pelvis. The first group is characterized by the full development of
this union, both pubis and ischium entering into the symphysis. The
tympanum remains as a ring within an auditory bulla; the orbit is
either surrounded by bone, or separated from the hinder part of the
skull by a post-orbital process of the frontal; the upper molars have
broad 5-cusped crowns with a W-shaped pattern; and the intestine is
generally furnished with a caecum. The first family of this group is
the _Tupaiidae_, represented by the tree-shrews, or tupaias, of the
Indo-Malay countries, characterized by the complete bony ring round
the eye-socket, the freedom of the fibula from the tibia in the
hind-limb, and the absence of any marked elongation of the tarsus. The
dental formula is _i._ 2/3, _c._ 1/1, _p._ 3/3, _m._ 3/3, total 38. In
appearance and habits tree-shrews are extremely like squirrels,
although they differ, of course, _in toto_ as regards their dentition.
A large number of species are included as the typical genus _Tupaia_,
which ranges from north-eastern India to the great Malay Islands. In
these animals the tail has a fringe of long hairs on opposite sides
throughout its length. In the pen-tailed, tree-shrew (_Ptilocercus
lowii_), fig. 1, the only representative of its genus, and a native of
Sumatra, Borneo and the Malay Peninsula, the fringes of long hair are
confined to the terminal third of the tail. There are also differences
in the skulls of the two genera. A third genus, _Urogale_, represented
by _U. cylindrura_ of the mountains of Mindanao, in the Philippines,
and _U. everetti_, of Borneo, has been established for the
round-tailed tupaias, in which the tail is uniformly short-haired, and
the second upper incisor and the lower canines are unusually large,
the third lower incisor being proportionately small, and also erect,
while the second upper incisor resembles a canine. (See TREE-SHREW.)

In Africa the tupaias are apparently represented by the
jumping-shrews, or elephant-shrews (so called from their elongated
muzzles), constituting the family _Macroscelididae_. From the
_Tupaiidae_ the members of this family are readily distinguished by
the fact that the socket of the eye, in place of having a complete
bony ring, is separated from the hinder part of the skull merely by a
post-orbital process of the frontal bone, and also by the more or less
marked elongation of the tarsus or lower portion of the hind-limb;
another feature being the union of the lower ends of the tibia and
fibula. As indicated by one of their names, the members of the group
leap after the fashion of gerbils, or jerboas, and hence walk much
more on their toes than the majority of the order. In the typical
genus _Macroscelides_, which ranges all over Africa and has numerous
specific representatives, the dental formula is _i._ 3/3, _c._ 1/1,
_p._ 4/4, _m._ 2/(2 or 3), total 40 or 42; while there are five toes
to each foot, and the lower ends of the radius and ulna are united. In
_Petrodromus_ (fig. 2) of East Africa, there are only four front-toes,
and the hairs on the lower part of the tail form stiff bristles, with
swollen tips; the dental formula being the same as that of those
species of _Macroscelides_ as have only two lower molars. A further
reduction of the number of the digits takes place in the long-nosed
jumping-shrews of the genus _Rhynchocyon_, which are larger animals
with a much longer snout, only four toes to each foot, and a dental
formula of _i._ (1 or 0)/3, _c._ 1/1, _p._ 4/4, _m._ 2/2, total 36 or
34. Some of the species, all of which are East African, differ from
the members of the typical genus by the deep rufous brown instead of
olive-grey colour of their coat. (See JUMPING-SHREW.)

In the second group, which includes all the other members of the
order, the pelvic symphysis is either lacking or formed merely by the
epiphyses of the pubes; the orbit and temporal region of the skull are
confluent; and, except in the _Talpidae_ and _Chrysochloridae_, the
tympanum is ring-like, the tympanic cavity being formed by the
alisphenoid and basisphenoid bones. The upper molars are triconodont,
being either of the typical or a modified form of what is known as
the tritubercular sectorial type. There is no caecum.

Moles.

The first representatives of this group are the moles, or _Talpidae_,
in which the lower ends of the tibia and fibula are united (fig. 3, t,
fb), there is a descent of the testes, the tympanum forms a
bladder-like bulla, the zygomatic, or cheek-arch, although slender, is
complete, there is no pelvic symphysis, the upper molars are
five-cusped, and the first upper incisor is simple, and the lower
vertical. In habits the majority of the family are burrowing, but a
few are aquatic; and all feed on animal substances. The distribution
is limited to the temperate regions of Europe, Asia and North America.

Throughout the family the eyes are minute, and in some species are
covered with skin; the ears are short and hidden in the fur; and the
fore-limbs are generally more or less modified for digging.

The true moles of the genus _Talpa_ are the typical representatives of
the first subfamily, or _Talpinae_, in which the clavicle (fig. 3,
cl.) and humerus (h) are very short and broad, while there is an
additional sickle-like bone (fc) on the inner side of the fore-foot.
In Talpa itself the first upper incisor is but little larger than the
second, the fore-foot is very broad, and the dental formula is _i._
2/2, _c._ 1/(1 or 0), _p._ 3/3, 3/4, or 4/4, _m._ 3/3. There are about
a dozen species, all confined to the Old World. The variation in the
dental formula of some of the best known of these is as follows:--

_i._ 3/3, _c._ 1/0, _p._ 4/4, _m._ 3/3 X 2 (_T. wogura_, _robusta_).
_i._ 3/3, _c._ 1/1, _p._ 4/4, _m._ 3/3 X 2 (_T. europaea_, _caeca_,
_romana_, _longirostris_, _micrura_).
_i._ 3/3, _c._ 1/1, _p._ 3/4, _m._ 3/3 X 2 (_T. leucura_, _leptura_).
_i._ 3/3, _c._ 1/1, _p._ 3/3, _m._ 3/3 X 2 (_T. moschata_).

Except in _T. europaea_, the eyes are covered by a membrane. In _T.
micrura_ the short tail is concealed by the fur. _T. europaea_ extends
from England to Japan.

_T. caeca_ and _T. romana_ are found south of the Alps, the remaining
species are all Asiatic, two only--_T. micrura_ and _T.
leucura_--occurring south of the Himalaya.

The genus may be split up into subgenera corresponding with the above
table; these subdivisions being sometimes accorded full generic rank.
For instance the Japanese _T. wogura_ and the Siberian _T. robusta_
are often referred to under the ill-sounding titles of _Mogera wogura_
and _M. robusta_.

Referring more fully to the European species, it may be mentioned that
the mole exhibits in its organization perfect adaptation to its mode
of life. In the structure of the skeleton striking departures from the
typical mammalian forms are noticeable. The first sternal bone is so
much produced as to extend forward as far as a vertical line from the
second cervical vertebra, carrying with it the very short almost
quadrate clavicles, which are articulated with its anterior extremity
and externally with the humeri, 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 little to the 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 lever power; and, thirdly, although the entire limb is
relatively 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, we find the hind-limbs 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
acetabulum 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 due to the humerus, which, like the clavicle, is so
reduced in length as to present the appearance of a flattened X-shaped
bone, with prominent ridges and deep depressions for the attachments
of powerful muscles. Its upper extremity presents two rounded
prominences; the smaller, the true head of the bone, articulates as
usual with the scapula; the larger, which is the external tuberosity
rounded off, forms a separate joint with the end of the clavicle. This
double articulation gives the rigidity necessary to support the great
lateral pressure sustained by the fore-limb in excavating. The bones
of the fore-leg are normal, but those of the fore-foot are flattened
and laterally expanded. The great width of the fore-foot is also
partly due to the presence of a peculiar bone on the inner side of the
palm and articulating with the wrist.

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 iliac bone.
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 hypapophysial sesamoid ossicle.
ol, Olecranon.
p, Pubic bone 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 falciform) in the manus.
sc, Scapula.
s.h, Scapular articulation of the humerus.
t, Tibia.
u, Ulna.]

The muscles acting on these modified limbs are homologous with those
of cursorial insectivora, differing only in their relative
development. The tendon of the biceps traverses a long bony tunnel,
formed by the expansion of the margin of the bicipital groove for the
insertion of the pectoralis major muscle; the anterior division of the
latter muscle is unconnected with the sternum, extending across as a
band between the humeri, and co-ordinating the motions of the
fore-limbs. The teres major and latissimus dorsi muscles are of
immense size, inserted into the prominent ridge below the pectoral
attachment, and are the principal agents in the excavating action of
the limb. The cervical muscles connecting the slender scapulae, and
through them the fore-limbs, with the centre line of the neck and with
the occiput are large, and the ligamentum nuchae between them is
ossified. The latter condition appears to be due to the prolongation
forwards of the sternum, preventing flexion of the head downwards; and
accordingly, the normal office of the ligament being lost, it
ossifies, and affords a fixed point for the origins of the
superficial cervical muscles.

The skull is long, with slender zygomatic arches; the nasal bones are
strong and early become united, and in front of them the nostrils are
continued forwards in tubes formed of thick cartilage, the septum
between which becomes partially or wholly ossified beneath. There are
7 cervical, 13 dorsal, 6 lumbar, 6 sacral and 10-12 caudal vertebrae;
of the dorsal and lumbar there may be one more or less. The sacral
vertebrae are united by their expanded and compressed spinous
processes, and all the others, with the exception of the cervical, are
closely and solidly articulated together, so as to support the
powerful propulsive and fossorial actions of the limbs. The upper
incisors are simple chisel-edged teeth; the canine is long and
two-rooted; then follow three subequal conical premolars, and a
fourth, much larger, and like a canine; these are succeeded by three
molars with W-shaped cusps. In the lower jaw the three incisors on
each side are slightly smaller, and slant more forwards; close behind
them is a tooth which, though like them, must, from its position in
front of the upper canine, be considered as the canine; behind it, but
separated by an interval, is a large double-rooted conical tooth, the
first premolar; the three following premolars are like the
corresponding teeth above, but smaller, and are succeeded, as above,
by the three molars. See MOLE.

In the other members of the _Talpinae_, which are North American, the
first upper incisor is much taller than the second. They include the
curious star-nosed mole (_Condylura cristata_), which has the typical
series of 44 teeth and a series of fleshy appendages round the
extremity of the snout; the species known as _Scapanus townsendi_ and
_Parascalops americanus_, each representing a genus by itself, and
characterized by the absence of nasal appendages and the presence of
only two pairs of lower incisors; and, finally, _Scalops aquaticus_,
in which the dentition is further reduced by the loss of the lower
canine, the total number of teeth thus being forty.

Forming a transition to the subfamily _Myogalinae_, in which the
clavicle and humerus are typically of normal form, and there is no
sickle-shaped bone in the fore-foot, is the Chinese mole (_Scaptonyx
piscicauda_), characterized by having the clavicle and humerus of the
true mole-type, but the foot like that of the under-mentioned
_Urotrichus_. The relative proportions of the first and second upper
incisors are also as in _Talpa_, but there are only two pairs of lower
incisors.

Among the more typical _Myogalinae_, mention may be made of _Dymecodon
pilirostris_, from Japan, representing a genus by itself; nearly
allied to which are the shrew-moles, as represented by the small and
long-tailed _Urotrichus_ of Japan, with incisors 2/1 and premolars
4/3, and _U. (Neurotrichus) gibbsi_ of North America, in which the
premolars are 3/4. A still more interesting form is the Tibetan
_Uropsilus soricipes_, a non-burrowing species, with the external
appearance of a shrew combined with the skull of a mole, the feet
being much narrower than in _Urotrichus_, and the dental formula _i._
2/1, _c._ 1/1, _p._ 3/3, _m._ 3/3.

The typical representatives of the subfamily are the two European
desmans, _Myogale moschata_ and _M. pyrenaica_, which are aquatic in
habits and have the feet webbed and the full series of 44 teeth. The
former is by far the largest member of the whole family, its total
length being about 16 in. 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,
forming 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 Pyrenees, is much smaller, has a
cylindrical tail, and a relatively long snout.

Shrews.

The Shrew-mice, or, shortly, shrews (_Soricidae_), are closely related
to the _Talpidae_, with which they are connected by means of some of
the subfamily _Myogalinae_. They are, however, distinguished by the
ring-like tympanic, the incompleteness of the zygomatic arch, the
tubercular-sectorial type of upper molar, the two-cusped first upper
incisor, and the forward direction of the corresponding lower tooth.
As a rule they are terrestrial, but a few are aquatic.

The dentition (fig. 5) is characteristic, and affords one of the chief
means of classifying this exceedingly difficult group of mammals.
There are no lower canines, and always six functional teeth on each
side of the lower jaw, but in some rare instances an additional
rudimentary tooth is squeezed in between two of the others. The first
pair of teeth in each jaw differ from the rest; in the upper jaw they
are hooked and have a more or less pronounced basal cusp; in the lower
jaw they are long and project horizontally forwards, sometimes with an
upward curve at the tip. Behind the first upper incisor comes a
variable number of small teeth, of which, when all are developed, the
first two are incisors, the third the canine, and the next two
premolars; behind these, again, are four larger teeth, of which the
front one is the last premolar, while the other three are molars. Thus
we have in the typical genus _Sorex_ (fig. 5) the dental formula _i._
3/2, _c._ 1/0, _p._ 3/1, _m._ 3/3, total 32, or twenty upper and
twelve lower teeth. The lower formula, as already stated, is constant,
but the number of the upper series varies from the above maximum of
twenty to a minimum of fourteen in _Diplomesodon_ and _Anurosorex_, in
which the formula is _i._ 2, _c._ 1, _p._ 1, _m._ 3. From the relation
of the fourth upper tooth to the premaxillo-maxillary suture it has
been supposed that shrews, like many polyprotodont marsupials, have
four pairs of upper incisors; but this is improbable, and the formula
is accordingly here taken to follow the ordinary placental type.

Shrews may be divided into two sections, according as to whether the
teeth are tipped with brownish or reddish or are wholly white, the
former group constituting the _Soricinae_ and the latter the
_Crocidurinae_.

In the red-tipped group is the typical genus _Sorex_, which ranges
over Europe and Asia north of the Himalaya Mountains to North America.
There are twenty upper teeth with the formula given above, the ears
are well developed, the tail is long and evenly haired, and the
aperture of the generative organs in at least one of the sexes is
distinct from the vent. The common shrew-mouse (_Sorex araneus_) has a
distribution co-extensive with that of the genus in the Old World, and
the North American _S. richardsoni_ can scarcely be regarded as more
than a local race. A few species, such as _Sorex hydrodomus_ of Alaska
and _S. palustris_ of the United States, have fringes of long hairs on
the feet, and are aquatic in habit. The latter has been made the type
of the genus _Neosorex_, but such a distinction, according to Dr J. E.
Dobson, is unnecessary. The same authority likewise rejects the
separation of the North American _S. bendirei_ as _Atophyrax_,
remarking that this species is an inhabitant of marshy land, and
appears to present many characters intermediate between _S. palustris_
and the terrestrial species of the genus, differing from the former in
the absence of well-defined fringes to the digits, but agreeing with
it closely in dentition, in the large size of the infra-orbital
foramen, and in the remarkable shortness of the angular process of the
lower jaw. In India and Burma the place of _Sorex_ is taken by
_Soriculus_, in which the upper teeth are generally 18, although
rarely 20, and the generative organs have an opening in common with
the vent after the fashion of the monotreme mammals. The latter
feature occurs in the North American _Blarina_, which is characterized
by the truncation of the upper part of the ear and the short tail, the
number of upper teeth being 20 or 18. Another American genus,
_Notiosorex_, in which the ear is well developed and the tail medium,
has only 16 upper teeth. From all the rest of the red-toothed group
the water-shrew, _Neomys_ (or _Crossopus_) _fodiens_, of Europe and
northern Asia, differs by the fringe of long hairs on the lower
surface of the tail; the number of upper teeth being 18.

In the white-toothed, or crocidurine, group, the small African genus
_Myosorex_, which has either 18 or 20 upper teeth, includes
long-tailed and large-eared species in which the aperture of the
generative organs and the vent, although close together, are yet
distinct. In the musk-shrews (_Crocidura_), on the other hand, which
are common to Europe, Asia and Africa, the reproductive organs and the
alimentary canal discharge into a common cloaca, the long tail is
sparsely covered with long and short hairs, there are anal glands
secreting a strong musky fluid, and the number of upper teeth is 16 or
18. _Diplomesodon pulchellus_ of the Kirghiz steppes, has, on the
other hand, only 14 upper teeth, and is further characterized by the
moderately long tail and the hairy soles of the hind-feet. Another
genus is represented by the Tibetan _Anurosorex squamipes_, which has
the same dental formula, but a mole-like form, rudimentary tail and
scaly hind-soles. Lastly, we have two Asiatic mountain aquatic
species, _Chimarrogale himalayaca_ of the Himalayas and _Nectogale
elegans_ of Tibet, which have fringed tails like the European
water-shrew, and 16 upper teeth, the former characterized by the small
but perfect external ears, and the latter (fig. 6) by the absence of
the ears and presence of adhesive disks on the feet.

It will be seen that the red- and the white-toothed series have
parallel representative forms, which may indicate that the division of
the family into the two groups is one based rather on convenience than
on essential differences. See SHREW.

From the shrews, the hedgehogs and gymnuras, or rat-shrews,
collectively forming the family _Erinaceidae_, differ structurally by
the broader ring made by the tympanic, the complete zygomatic arch,
the five-cusped broad upper molars, and the presence of a short pubic
symphysis. At the present day they are an exclusively Old World group.

Hedgehogs.

The typical group, or _Erinaceinae_, is represented only by the
hedgehogs, with the one genus _Erinaceus_, easily recognized by their
spiny coats, and further characterized by the rudimentary tail, the
presence of vacuities in the palate, and the broad pelvis. Hedgehogs
(_Erinaceus_) have the dental formula i. 2/2, c. 1/1, p. 3/2, m. 3/3,
and are represented by over a score of species, distributed throughout
Europe, Africa and the greater part of Asia, but unknown in
Madagascar, Ceylon, Burma, Siam, the Malay countries, and, of course,
Australia. All the species resemble one another in the armour of
spines covering 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 these spines, the skin of the back being
brought downwards and inwards over the head and tail so as to include
the limbs by the action of special muscles.

Curiously enough the European hedgehog (_E. europaeus_) is the most
aberrant species, differing from all the rest in the peculiarly-shaped
and single-rooted third upper incisor and first premolar (fig. 7, A),
and in its very coarse harsh fur. The dentition of the long-eared
Indian _E. grayi_ (fig. 7, B) may, on the other hand, 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 _E. pictus_. The former species, limited
to South India, is further distinguished by the absence of the jugal
bone. Of African species, _E. diadematus_, with long frontal spines,
is probably the commonest, and _E. albiventris_ has been made the type
of a separate genus on account of the total absence of the first
front-toe. See HEDGEHOG.

Rat-shrew.

The members of the second subfamily, _Gymnurinae_, are more or less
rat-like animals, confined to the Malay countries, and easily
distinguished from the hedgehogs by the absence of spines among the
fur and the well-developed tail. They also lack vacuities in the
palate, and have a long and narrow pelvis. The typical representative
of the family is the greater rat-shrew, or greater gymnura (_Gymnura
rafflesi_) a creature which may be compared to a giant shrew, and
whose colour is partly black and partly white, although a uniformly
pale-coloured race. (_G. r. alba_) inhabits Borneo. In common with the
next genus, it has the full series of 44 teeth; and its range extends
from Tenasserim and the Malay Peninsula to Sumatra and Borneo, the
island individuals being stated to be considerably larger than those
from the mainland. In this species the length of the tail is about
three-fourths that of the head and body; but in the lesser rat-shrew
(_Hylomys suillus_), ranging from Burma and the Malay Peninsula to
Java and Sumatra, the former dimension is only about one-sixth of the
latter. In the Philippines the group is represented by _Podogymnura
truei_, distinguished from the other genera by the great elongation of
the hind-foot, the tail being likewise long. There are only three
pairs of premolars in each jaw.

Insectivorous Otter.

In the remaining families of the Insectivora the tibia and fibula may
be either separated or united at the lower end; there is no descent of
the testes, except in _Solenodon_; a short symphysis is formed by the
junction of the pubic epiphyses; and the upper molars are generally
small, and triangular, with three cusps arranged in a V. The first
family, _Potamogalidae_, is represented by the otter-like _Potamogale
velox_ of the rivers of West Africa (fig. 8), distinguished from all
other members of the order by the absence of clavicles. The tibia and
fibula are united interiorly, the skull has a ring-like tympanic, no
zygomatic arch, and the upper molars are of the tuberculo-sectorial
type, with broader crowns than in the following families. The dental
formula is i. 3/3, c. 1/1, p. 3/3, m. 3/3, total 40. This animal
inhabits the banks of streams in west equatorial Africa, and its whole
structure indicates an aquatic life. It is nearly 2 ft. 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
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.

Tenrec.

In the remaining groups the upper molars form narrow V's of the true
tritubercular type. The family, _Centetidae_, represented by the
tenrec and a number of allied animals from Madagascar, is specially
characterized by the ring-like tympanic, and the absence of a
zygomatic arch and of any constriction of the skull behind the orbits,
and the presence of teats on the breast as well as the abdomen. In the
more typical members of the family the tibia and fibula are separate,
and, as in hedgehogs, spines are mingled with the fur. The true or
great tenrec (_Centetes ecaudatus_), alone representing the typical
genus, has the dental formula _i._ (3 or 2)/3, _c._ 1/1, _p._ 3/3, m.
(3 or 4)/(3 or 4), total 38, 40, 42 or 44. The fourth lower molar,
when developed, does not appear till late in life. Of the long and
sharp canines, the tips of the lower pair are received into pits in
the upper jaw (fig. 9). The creature grows to a length of aoout a
foot. The young have strong white spines arranged in longitudinal
lines along the back, but these are lost in the adult which has only a
crest of long rigid hairs on the nape of the neck. The lesser tenrecs,
_Hemicentetes semispinosus_ and _H. nigriceps_, are distinguished by
the persistence of the third upper incisor and the form of the skull.
The two species are much smaller than the great tenrec, and spines are
retained in the adult on the body. The hedgehog-tenrec, _Ericulus
setosus_, has the whole upper surface, and even the short tail,
densely covered with close-set spines. The facial bones are much
shorter than in the preceding genera, and the first upper incisors are
elongated; while there are only two pairs of incisors in each jaw.
Judging from the slight development of the cutaneous muscles compared
with those of the hedgehog, it would seem that these creatures cannot
roll themselves completely into balls in hedgehog-fashion. A second
species of this genus, _Ericulus (Echinops) telfairi_, has two, in
place of three, pairs of molars, thus reducing the total number of
teeth to 32. Moreover, the zygomatic arches of the skull are reduced
to mere threads. Here should perhaps be placed _Geogale aurita_, a
small long-tailed Malagasy insectivore, with 34 teeth, and no spines;
the tibia and fibula being separate. It has been classed in the
_Potamogalidae_, but from its habitat such a reference is improbable.
The absence of spines may entitle it to separation from the
_Centetinae_, so that it should perhaps be regarded as representing a
subfamily, _Geogalinae_, by itself.

The absence of spines coupled with the union of the tibia and fibula
form the leading characteristics of the subfamily _Oryzorictinae_,
typified by the rice-tenrecs _Oryzorictes_, of which there are several
species. These creatures, which excavate burrows in the rice-fields of
Madagascar, are somewhat mole-like in appearance, but have tails of
considerable length. In the typical _O. hova_ the fore-feet are
five-toed, but in _O. tetradactylus_ the number of front digits is
reduced to four. The long-tailed tenrecs (_Microgale_) are represented
by fully half-a-dozen species with tails of great length; that
appendage in the typical _M. longicaudata_ being more than double the
length of the head and body, and containing no fewer than forty-seven
vertebrae. The teeth are generally similar to those of _Centetes_, but
are not spaced in front; their number being _i._ 3/3, _c._ 1/1, _p._
3/3, _m._, 3/3, total 40, or the same as in _Oryzorictes_. Finally,
_Limnogale mergulus_, a creature about the size of a black rat, has
webbed toes and a laterally compressed tail, evidently adapted for
swimming. See TENREC.

Solenodon.

All the foregoing are natives of Madagascar. It has been suggested
however, that two remarkable West Indian insectivores, namely
_Solendon cubanus_ of Cuba (fig. 11) and _S. paradoxus_ of Hayti,
should be regarded as representing merely a subfamily of _Centetidae_.
It is true that the main features distinguishing these strange
creatures from the Malagasy representatives of that family are the
constriction of the skull behind the orbits, the descent of the testes
into the perineum, and the post-inguinal position of the teats, and
that none of these are of very great importance. But the geographical
positions of the two groups are so widely sundered that it seems
preferable to await further evidence before definitely assigning the
two to a single family; and the family _Solenodontidae_ may
accordingly be retained for the West Indian animals. Solenodons, which
look like huge long-nosed, parti-coloured rats, have the tibia and
fibula separate, and the same dental formula as _Microgale_. Each of
the two species (which differ in colour and the quality of the fur)
has a long cylindrical snout, an elongated naked tall, feet formed for
running, and the body clothed with long, coarse fur. The position of
the teats on the buttocks is unique among Insectivora. The first upper
incisors are much enlarged, and like the other incisors, canines and
premolars, closely resemble the corresponding teeth of _Myogale_; the
second lower incisors are much larger than the upper ones, and
hollowed out on the inner side.

Golden Mole.

The last family, _Chrysochloridae_, is represented by the golden moles
of South and East Africa, which differ from the _Centetidae_ and
_Solenodontidae_ by the development of a bulla to the tympanic, and
the presence of a zygomatic arch to the skull; the tibia and fibula
being separate, and the symphysis of the pelvis formed merely by
ligament. The skull is not constricted across the orbits. The teats,
which are placed both on the breast and in the groin, are situated in
shallow depressions. The ears are buried in the fur, and the eyes
concealed beneath the skin; the feet are four-toed and provided with
powerful claws for burrowing in the fashion of the mole, but it is
interesting to note that the skeleton is modified for the same purpose
in a manner quite different from that obtaining in the latter animal.
These animals derive their name from the metallic iridescence of the
fur of most of the species. In the more typical species the dental
formula is the same as in _Microgale_, that is to say, there are 40
teeth. In other species, which it has been proposed to separate as
_Amblysomus_, there are, however, only 36 teeth, owing to the absence
of the last pair of molars. The group is evidently nearly related to
the _Centetidae_--most nearly perhaps to the _Oryzorictinae_.

_Fossil Insectivora._

Some years ago Dr F. Ameghino, of Buenos Aires, described from the
Tertiary formation of Santa Cruz, in Patagonia, the remains of an
insectivore under the name of _Necrolestes_. The occurrence of a
member of the Insectivora in these beds is remarkable, since this
group is represented at the present day in South America only by a
shrew or two which have wandered from the north. Dr Ameghino expressed
his belief that the extinct Patagonian insectivore was nearly related
to the golden moles, and although this opinion appears to have been
withdrawn, Professor W. B. Scott states that he is convinced of the
close affinity existing between _Necrolestes_ and _Chrysochloris_.
Although this view may not be accepted, it must be remembered that it
represents the opinion of a palaeontologist who has had better
opportunities than most of his fellow-workers of forming a trustworthy
judgment. So convinced is Dr Scott of the closeness of the
relationship between _Necrolestes_ and the golden moles that he
regards it as rendering probable the former existence of a direct
land-connexion between Africa and South America. There is no reason,
he says, to suppose that the track of migration could have been by way
of Europe and North America, for no trace of the group has been found
anywhere north of the equator. This supposed connexion between Africa
and South America in Tertiary times has often been suggested, and is
supported by many independent lines of evidence; and the presumed
affinity between the two mammals here referred to adds to the weight
of such evidence.

The discovery in the Oligocene Tertiary deposits of Dakota of the
remains of a species of hedgehog is a fact of great interest, for the
hedgehog-tribe (_Erinaceidae_) is at the present day an exclusively
Old World group. The discovery of the fossil American species, which
has been made the type of a new genus under the name of _Protherix_,
serves to strengthen the view that the northern countries of the
Western and Eastern hemispheres form a single zoological region; and
that formerly there was comparatively free communication between them
in the neighbourhood of Bering Sea, under climatic conditions which
permitted of temperate forms passing from one continent to the other.
As might have been expected, remains of hedgehog-like mammals have
been obtained in the Tertiary deposits of Europe. Among these,
_Palaeoerinaceus_, from the Upper Oligocene of France, seems scarcely
separable from the existing genus. _Necrogymnurus_ (_Neurogymnurus_)
from the Lower Oligocene, of the same country, appears to be allied to
_Hylomys_, which is itself the most generalised of the family, so that
the extinct genus, of which _Caluxotherium_ is a synonym, may
represent the ancestral type of the _Erinaceidae_. The genus
_Galerix_, or _Lanthanotherium_, of the Oligocene, which has the
typical series of 44 teeth, a bony ring round the orbit, and conjoint
tibia and fibula, has been regarded as representing the _Tupaiidae_
and _Macroscelididae_, but is more probably referable to the
_Erinaceidae_, being apparently akin to _Gymnura_. The moles are
represented in the French Oligocene by _Amphidozotherium_ and in the
Miocene by _Talpa_, while in the North American early Tertiary we have
the primitive _Talpavus_. Shrews are also known from the Lower
Oligocene upwards both in the eastern and western hemispheres. Of the
Lower Eocene _Adapisorex_, with the typical 22 lower teeth,
_Adapisoriculus_ and _Orthaspidotherium_, all from France, the
affinities are quite uncertain. The American Oligocene _Leptictis_,
with i. 2, c. 1, p. 4, m. 3 in the upper jaw, and Ictops, with i. 3/2,
c. 1/1, p. 4/4, m. 3/3, may be insectivorous mammals, with affinities
to the creodont Carnivora. It is, indeed, probable that not only is
there a relationship between the Creodonta and the Insectivora, but
also one between the latter and the Marsupialia, so that the marked
similarity between the cheek-teeth of the insectivorous
_Chrysochloris_ and the Marsupial _Notoryctes_ may be due to genetic
relationship. That the bats and the flying-lemur are descendants of
the Insectivora cannot be doubted.

BIBLIOGRAPHY.--G. E. Dobson, "Monograph of the Insectivora" (London,
1883-1890); W. Leche, "Zur Morphologie des Zahnsystems der
Insectivoren," _Anatom. Anzeiger_ (xiii. 1 and 514, 1897); C. J.
Forsyth-Major, "Diagnoses of New Mammals from Madagascar." _Ann. Mag.
Nat. Hist._ ser. 6. vol. xviii. pp. 318 and 461 (1896): A. A. Mearns,
"Descriptions of New Mammals from the Philippine Islands," _Proc. U.S.
Museum_ (xxviii. 425, 1905). (R. L.*)

INSECTIVOROUS PLANTS. Insectivorous or, as they are sometimes more correctly termed, carnivorous plants are, like the parasites, the climbers, or the succulents, a physiological assemblage belonging to a number of distinct natural orders. They agree in the extraordinary habit of adding to the supplies of nitrogenous material afforded them in common with other plants by the soil and atmosphere, by the capture and consumption of insects and other small animals. The curious and varied mechanical arrangements by which these supplies of animal food are obtained and utilized are described under the headings of the more important plants.

The best known and most important order of insectivorous plants--Droseraceae--includes six genera: _Byblis_, _Roridula_, _Drosera_, _Drosophyllum_, _Aldrovanda_ and _Dionaea_, of which the last three are monotypic, i.e. include only one species. The Sarraceniaceae contain the genera _Sarracenia_, _Darlingtonia_, _Heliamphora_, while the true pitcher plants or Nepenthaceae consist of the single large genus _Nepenthes_. These three orders are closely allied and form the series Sarraceniales of the free-petalled section (Choripetalae) of Dicotyledons. The curious pitcher-plant, _Cephalotus follicularis_, comprises a separate natural order Cephalotaceae, closely allied to the Saxifragaceae. Finally the genera _Pinguicula_, _Utricularia_, _Genlisea_ and _Polypompholix_ belong to the gamopetalous order Lentibulariaceae.

While the large genus _Drosera_ has an all but world-wide
distribution, its congeners are restricted to well-defined and usually
comparatively small areas. Thus _Drosophyllum_ occurs only in Portugal
and Morocco, _Byblis_ in tropical Australia, and, although
_Aldrovanda_ is found in Queensland, in Bengal and in Europe, a wide
distribution explained by its aquatic habit, _Dionaea_ is restricted
to a few localities in North and South Carolina. _Cephalotus_ occurs
only near Albany in Western Australia, _Heliamphora_ on the Roraima
Mountains in Venezuela, _Darlingtonia_ on the Sierra Nevada of
California, and these three genera too are as yet monotypic; of
_Sarracenia_, however, there are seven known species scattered over
the eastern states of North America. The forty species of _Nepenthes_
are mostly natives of the hotter parts of the Indian Archipelago, but
a few range into Ceylon, Bengal, Cochin China, and some even occur in
tropical Australia on the one hand, and in the Seychelles and
Madagascar on the other. _Pinguicula_ is abundant in the north
temperate zone, and ranges down the Andes as far as Patagonia; the 250
species of _Utricularia_ are mostly aquatic, and some are found in all
save polar regions; their unimportant congeners, _Genlisea_ and
_Polypompholix_, occur in tropical America and south-western Australia
respectively. It is remarkable that all the insectivorous plants agree
in inhabiting damp heaths, bogs, marshes and similar situations where
water is abundant, but where they are not brought into contact with
the plenteous supply of inorganic nitrogenous food as are the roots of
terrestrial plants.

INSEIN, a town of British India, in the Hanthawaddy district of Burma, 10 m. N.W. of Rangoon; pop. (1901) 5350. It is an important railway centre, containing the principal workshops of the Burma railway company, also a government engineering school, a reformatory school and the largest gaol in the province.

INSOMNIA, or deprivation of sleep (Lat. _somnus_), a common and troublesome feature of most illnesses, both acute and chronic. It may be due to pain, fever or cerebral excitement, as in _delirium tremens_, or to organic changes in the brain. The treatment, when failure to sleep occurs in connexion with a definite illness, is part of the treatment of that illness. But there is a form of sleeplessness not occurring during illness to which the term "insomnia" is commonly and conveniently applied. It must not be confounded with occasional wakefulness caused by some minor discomfort, such as indigestion, nor with the "bad nights" of the valetudinarian. Real insomnia consists in the prolonged inability to obtain sleep sufficient in quantity and quality for the maintenance of health. It is a condition of modern urban life, and may be regarded as a malady in itself. It is a potent factor in causing those nervous breakdowns ascribed to "overwork." It may occur as a sequel to some exhausting illness, notably influenza, which affects the nervous system long after convalescence. But it very often occurs without any such cause. Professional and business men are the most frequent sufferers. Insomnia is comparatively rare among the poor, who do little or no brain work. It may be brought on by some exceptional strain, by long-continued worry, or by sheer overwork. The broad pathology is simple enough. It has been demonstrated by exact observations that in sleep the blood leaves the brain automatically. The function is rhythmical, like all the vital functions, and the mechanism by which it is carried out is no doubt the vaso-motor system, which controls the contraction and dilation of the blood-vessels. In sleep the vessels in the brain automatically contract, but when the brain is working actively a plentiful supply of blood is required, and the vessels are dilated. If the activity is carried to great excess the vessels become engorged, the mechanism does not act and sleep is banished. In insomnia this condition has become fixed.

When a breakdown has happened or is pending the only treatment is complete rest, combined, if possible, with change of air and scene; but if the mischief has gone far it will take very long to repair, and may never be repaired at all. In no matter of health is the importance of "taking it early" more pronounced. Delay is the worst economy. A few days' holiday at the commencement of trouble may save months or years of enforced idleness. Sea-air sometimes acts like a charm. But if it is impossible to give up work and leave worry behind, even for a short time, sleep should be carefully wooed by every possible means. In the first place, plenty of time should be devoted to it, and no chance should be missed. That is to say, the night should not be curtailed at either end, and if sleepiness approaches in the daytime, as it often does, it should be encouraged. It is better to lie still at night and try to sleep than to give way to restlessness, and a few minutes snatched in the daytime, when somnolence offers the opportunity, has a restorative effect out of all proportion to the time occupied. Then all accidental causes of disturbance should be avoided. Lights and sounds should be excluded, comfort studied and digestion attended to. Fresh air is a great help. As much time should be spent out of doors as possible, and exercise, even to the point of fatigue, may be found helpful. But this requires watching: in some cases bodily exhaustion aggravates the malady. A little food (e.g. a glass of hot milk) immediately before going to bed is useful in inducing sleep, and persons who are apt to wake in the night and lie awake for hours may obtain relief by the same means. Hypnotic drugs, which have greatly multiplied of late years, should only be taken under medical advice. The real end to aim at is the restoration of the natural function, and the substitution of artificial sleep, which differs in character and effect; tends rather to prevent than to promote that end. It is often possible to induce sleep by rhythmic breathing.

INSPIRATION (Lat. _inspirare_, breathe upon or into), strictly the act of drawing physical breath into the lungs as opposed to "expiration." Metaphorically the term is used generally of analogous mental phenomena; thus we speak of a sudden spontaneous idea as an "inspiration." The term is specially used in theology for the condition of being directly under divine influence, as the equivalent of the Greek [Greek: theopneustia] (the adjective [Greek: theopneustos] is used of the Holy Scriptures in 2 Timothy iii. 16). Similar in meaning is [Greek: enthousiasmos], enthusiasm (from [Greek: enthousiazo] from [Greek: entheos]). Possession by the divine spirit ([Greek: pneuma]) was regarded as necessarily accompanied by intense stimulation of the emotions. The possibility of a human being becoming the habitation and organ of a divinity is generally assumed in the lower religions. In the popular religion of China some of the priests, the _Wu_, claim to be able to take up into their body a god or a spirit, and thereby to give oracles. In wild frenzy they rush about half naked with hair hanging loose, wounding themselves with swords, knives, daggers, and uttering all kinds of sounds, which are then interpreted by people who claim to be able to understand such divine speech. The Maoris at the initiation of the young men into the tribal mysteries sing a song, called "breath," to the mystic wind by which they believe their god makes his presence known. An Australian woman claimed to have heard the descent of the god as a rushing wind. In some savage tribes blood is drunk to induce the frenzy of inspiration; music and dancing are widely employed for the same purpose. Dionysus, the god of wine in Greece, was also the god of inspiration; and in their orgies the worshippers believed themselves to enter into real union with the deity. In Delphi the Pythia, the priestess who delivered the oracles, was intoxicated by the vapour which rose from a well, through a small hole in the ground. As the oracles were often enigmatic, they were interpreted by a _prophet_. In Rome the inspiration of Numa was derived from the nymph Egeria; and great value was attached to the books of the Cumaean Sibyl. In Arabia the _kahin_ (priest) was recognized as the channel of divine communication. Inspiration may mean only possession by the deity, or it may mean further that the person so possessed becomes the channel through which the deity reveals his word and will. (See J. A. Macculloch's _Comparative Theology_, chap. xv., 1902).

Prophecy in the Old Testament in its beginnings is similar to the phenomenon in other religions. Saul and his servant came to Samuel, the man of God, the seer, with a gift in their hands to inquire their way (1 Sam. ix. 8). The companies of prophets who went about the country in Samuel's time were enthusiasts for Yahweh and for Israel. When Saul found himself among them he was possessed by the same spirit (1 Sam. x. 10, 11.). The prophesying in which he took part probably included violent movements of the body, inarticulate cries, a state of ecstasy or even frenzy. The phrase "holy spirit" in Acts, as applied to the Apostolic Church, probably indicates a similar state of religious exaltation; it was accompanied by speaking with tongues, inarticulate utterances, which needed interpretation (1 Corinthians xiv. 27). In every religious revival, when the emotions are deeply stirred, similar phenomena are met with. Such a movement was Montanism in the 3rd century. At the Reformation, while Luther was at the Wartburg, fanaticism broke out, and spread from Wittenberg; prophets went about declaring the revelations which they had received. The Evangelical Revival in the 18th century also had its abnormal religious features. The Revival in Scotland in 1860 was marked by one curious feature--the Gospel dance--when in their excitement men and women got up and spun round and round till they were exhausted. Spontaneous praise and prayer marked the revival in Wales in 1905-1906.