The first of these divisions, the Lemuridae
is more widely separated, anatomically, from the other two, than these
are from one another, (On the strength of these differences M. Gratiolet relegated the Lemurs to
and Mr. Mivart, in his valuable paper "On the Axial Skeleton
in the Primates," publislied in the Proceedings of the Zoological Society
for 1855, divides the Primates
into two sub-orders, Lemuroidea
) and it contains some forms which
very closely approximate to the Insectivora
, while others are
nearly affined to the Rodentia.
All the Lemuridae
are habitually quadripedal, have the
integument furry, and are usually provided with long tails
which are never prehensile. They are devoid of cheekpouches
and of callous patches upon the integument covering
The fore-limbs are shorter than the hind-limbs. In the
foot, the hallux is large and opposable, and the second digit
differs from the rest in size, and in the claw-like form of its
nail. The fourth digit is usually longer than the others, the
difference being especially marked in the pes.
In the skull, the brain-case is small relatively to the face,
and is contracted anteriorly. If a straight line drawn from
a point midway between the occipital condyles, through the
median plane of the skull, to the junction of the ethmoid and
presphenoid, in the floor of the cerebral cavity, be termed the basi-cranial axis
; and if the planes of the cribriform plate of
the ethmoid, of the tentorium cerebelli, and of the occipital
foramen, be respectively termed the ethmoidal, tentorial,
and occipital planes;
then, the greatest length of the cerebral
cavity hardly exceeds the length of the basi-cranial axis; and
the ethmoidal, tentorial, and occipital planes are very much
inclined to that axis. The upper aperture of the lachrymal
foramen lies upon the face, outside the front margin of the orbit.
The frontal and the jugal bones are united behind the orbit,
but a mere bar of bone results from their union; and it is
so narrow that the orbit and the temporal fossa are in free
communication. The bony palate is elongated, and, in many
species, its posterior free edge is thickened.
The lateral processes of the atlas are, usually, expanded.
The lumbar region of the spine is elongated; the vertebrae
composing it, in some cases, being as many as nine. There
are nine bones in the carpus. The ilia are narrow and elongated,
and the ischia are not everted. In most Lemurs, the
tarsal bones resemble those of the other Primates
; but, in Otolicnus
, they have undergone a modification, a
parallel towhich is not to be found among Mammals, but must
be sought among the Batrachia.
When the distance between
the heel and the digits is great in other Mammalia,
affects the matatarsal bones and not the tarsus; but, in
these Lemurs, the calcaneum and the naviculare are prolonged,
as they are in the Frogs.
, a process of the mucous membrane of the
floor of the mouth, developed between the apex of the tongue
and the symphysis of the mandible, acquires a considerable
size, and is often denticulated, or comblike, at its free end.
The stomach is simple, with the cardiac and pyloric apertures
approximated. The caecum is long, and has no vermiform
In many Lemurs (Stenops, Nycticebus, Perodicticus, Arctocebus,
) the great arteries and veins of the limbs break
up into retia mirabilia
formed of parallel branches.
The ventricles of the larynx may be enlarged, but there
are no great air-sacs, such as exist in many other Primates.
In the brain, the cerebral hemispheres are relatively small
and flattened, and have narrow and pointed frontal lobes.
They are so short as to leave the cerebellum largely uncovered.
The gyri and sulci are scanty, or absent, upon the outer surface
of the hemispheres, but the internal face exhibits the calcarine
sulcus. The large olfactory lobes project forward beyond
the cerebral hemispheres.
The pendent penis of the male commonly contains a bone;
the testes are lodged in a more or less complete scrotum; and
vesiculae seminales are generally present.
In the female, the uterus has two long cornua, and the
urethra traverses the clitoris. Sometimes there are one or
two pairs of teats on the abdomen, in addition to the ordinary
are distinguishable into two families, the Lemurini
and the Cheiromyini.
In the Lemurini,
the pollex is large, opposable, and almost
always has a broad, flat nail.
The usual dental formula is i.
/1.1 p.m. m.
5.5/5.5, or 6.6/6.6.
The upper incisors are vertical, and the pairs of opposite
sides are generally separated by an interval. The upper
canines are large and pointed, and very different from the
incisors. The lower incisors are close set, laterally compressed,
long and proclivous, and the canines, which resemble them in
form and direction, are closely applied to the outer incisors.
When six grinders are present, the anterior three are premolars.
The anterior premolars, and sometimes all of them, have
triangular and sharp-pointed crowns; the first premolar of the
lower jaw, in fact, resembles a canine, but its true nature is
shown bv its biting behind the upper canine, not in front of it.
Very generally the crowns of the upper molars are quadricuspidate,
and an oblique ridge passes from the antero-external
to the postero-internal cusp, as in the highest Primates;
while, in the lower jaw, there are either two transverse ridges,
or longitudinal crescents. The cusps of the molars are usually
much produced, as in the Insectivora.
In the Cheiromyini,
the pollex is not truly opposable, and
its nail is claw-like and resembles that of the other digits.
All the digits of the pes, except the hallux, have compressed,
claw-like nails. The middle digit of the manus is much more
slender than any of the others, and is longer than the fourth.
The long axis of the articular head of the mandible is anteroposterior.
The dentition differs from that of all the other
Lemurs (and indeed from that of all the other Primates
resembles that of the Rodents.
Thus there is only one pair of incisors in each jaw,(Among the Lemuridce,
the outer and upper incisors of Nycticebus
soon fall out. Lichanotus
have only one pair of incisors
in the mandible.) and
these grow from persistent pulps and have a thick layer of
enamel on their anterior faces, whence they wear to sharp
chisel-edges, like the incisors of the Rodentia
. No canines
are developed, and there are four grinders with simple crowns
on each side above and below.
The formula of the milk dentition is d.i.
are confined to Eastern Asia, Madagascar,
and South Africa; Madagascar presenting the greatest number
and diversity of genera and species.