obliterated before they reaob tbe apex, which is almost smooth. Each scale also in the
young state is marked by either one or three lines of growth. In M. pentadactyla,
but more especially in M. aurita, the scales get worn down into hexagons, and the
sharp points of the lateral line of scales in all the species, and which are especially
prominent in young and semi-adult examples of M. javanica, get so abraded by
friction that the sides of the tail become quite smooth.
In the young of all the species the scales are much more lightly coloured than
in the adults, but neither M. awrita nor M. javanica is ever so pale yellow as
M. pentadactyla. In the young of M. aurita the basal portion of the scales is
dark brown, but the remainder is more or less variegated with homy yellow which in
the tail scales is generally restricted to their margins. In M. pentadactyla there
is little or no variation in the pale olive-brown, but M. javanica resembles M. aurita
in the parti-colouring of its scales. In the adult of the latter, I have occasionally
observed the perfectly smooth scales very regularly marked with rather clear concentric
rings of pale yellow; whilst in others the centres of the scales outside
the limbs and on the -flanks are coloured pale yellowish, a similar distribution
of colour occurring also in M. javanica. In M. javanica, moreover, there is a
tendency in the yellow to spread over a series of scales involving considerable
areas, and this is most prevalent on the extremity of the ta il; and it was this
and some other characters that led Blyth to describe this form under the name
of M. leucu/ra.
As is well known, a number of strong yellowish hairs or bristles occur at the
base of each scale, generally arranged in three or four groups and projecting outwards
externally between the overlapping scales. In the adult the exposed portion of these
hairs is worn away by abrasion.
The head-scales clothe the upper surface of the head as far forwards as on
a line with the middle of the mouth, terminating in a single scale. Besides the
sides of the head and neck, chin, throat, chest, belly, and inside of the limbs, and
an extensive area around the vent, and all of which are destitute of scales, a scaleless
area occurs on the hind leg in the region of the knee-joint along the outside of
the limb, but it is more or less protected by the row of scales above it* but when
the limb is backwardly expanded to its utmost limit, this scaleless patch is
visible externally. No such patch occurs on the fore limb. Its function is to
permit of the inward bending and stowing away of the limb when the animal
is coiled up. All the scaleless parts are more or less clad with short reddish-
brown or yellowish hairs, which appear to be most numerous in sémi-adult
individuals, but the upper part of the nose is bare and destitute of hairs. The tip
of the nose over the nostril, the external skin of the nasal septum, the skin between
the lower anterior third of the nostrils and the upper lip, and the tip of the
lower lip, have a honeycombed appearance in M. pentadactyla, each cell, as it were,
having a central depression resembling the entrance to a glandular duct. The skin
behind and at the two posterior thirds of the nostrils and along the upper and
the lower lip is quite smooth. This smooth space extends behind the posterior end of
the nostril, where it impinges on the rough and haired skin of the scaleless portion
of the face. There is also a smooth patch on the centre of the chin. The skin of
the nose and lips in M. pentadactyla has a well-marked bluish colour contrasting
with the pale colour of the scaleless parts.
The eye is small, and is situated rather close to the ear, and the iris is generally
dark brown. The ear is moderately well developed, and more or less rounded in all the
species, and is clad with short, rather stout hairs. The palmar surface of the fore feet
has in its centre a few circular elevations marked by central depressions; the skin,
however, in M. pentadactyla is of the same uniform pale yellow colour as the scaleless
portions of the body. I t is unhardened by use, as these animals walk on the
terminal joints of the two outer toes and on the terminal halves of the claws of these
toes, the inner toes not touching the ground. The under surface of the hind foot
has a brown warty appearance, and the claws project only, a short way beyond the
thick pad which protects the bones of the feet. I t is divided into an inner portion,
swollen and round, and into an outer flattened portion. The whole of the plantar
surface reaches the ground.
With reference to the general osteologies! features of the three species, the
numerical variations in the vertebral column are not greater than what occur in
many well-recognised species of mammalia. Thus in M. pentadactyla there are
26 cervical and trunk vertebrae, excluding the sacral; in M. mrita 28 to 30; and
28 in M. javanica. In the first of these there are 14 ribs; in the second 15 to 17
well-developed costal elements, with a small rudimentary rib in the animal with 15,
and another has probably been lost; while in M. javcmica there are 14 well-formed
ribs, and a small terminal rib. The normal number of sacral vertebrae throughout
the species appears to be three, but in the adults it is extremely difficult to decide in
some instances between the sacral and pseudo-sacral elements; there would appear,
however, to be from one to three of the caudal vertebrae that unite with those
which are essentially sacral, and in such instances they become soldered to the
pelvis. In M. pentadactyla, if the sacrum is regarded as consisting of only three
vertebrae, then there are as many as 30 caudais, in M. aurita 27, and in M.
ja/oanica 29.
I t will be observed that the greater length of the tails of M. pentadactyla and
of M. javanica is not solely due to the greater number of the vertebrae, as there
are only two or "three more than in M. aurita. This circumstance is brought out
by comparing the respective lengths of the caudal vertebrae, as a whole, with the
remainder of the vertebral column. In M. pentadactyla the tail segments measure
23*75 inches to 19'25, the length of all the remaining vertebrae; in M. javanica
17-75 to 17-50; and in Jf. aurita 12-60 to 14. As the greater length of the caudal
portion in the two former cannot be accounted for by any increase in the number
of the vertebrae, the explanation of the length of the tails of these species is found in
the greater length and size of the bodies of the individual vertebrae, whereas the
comparative shortness of the tail of M. aurita is explained by the short and feeble
character of the vertebrae themselves.
TJ 2