antibrachium of which is gray. On the hinder quarters and outsides of the thighs
the terminal half of the hairs are wholly rufous-yellow, so that these portions
contrast forcibly with the former. In 0, the cheeks and supraorbital ridges are
surrounded w ith a fringe of long black hairs which are continued down to the
angle of the mouth, whereas in the other female there are only a few very short
black hairs in these situations. In both, the hairs half-way between the ear and
the angle of the mouth tend to form a whorl. The hair behind the ears and the
back part of the cheek are in 0 annulated in the former and yellowish in the
latter locality, but in * tbey are uniformly yellowish grey, and longer and more
wavy than in the former. In life, the face of 0 was seen to be more dusky1 than
is generally the case in M. rhesus, while in « it was pale, as in this species, and periodically
flushed with crimson, which did not occur in 0. The hair on the top of the
head in both is directed backwards. In both, the under parts and insides of the
limbs are very pale yellowish white with a silky lustre. In * there is an extensive
area external to and below the callosities, which is only sparsely covered with very
short obscure white hairs, while in 0 the region below and around the callosities is
clad with long rufous hairs.
Meas tjbbments. ■ 0-
Inches. Inches.
Length o f body, along side . • - • • • • . • •
„ of .tail' ■■ • • • ■ • - V B "
15-24
7-5
14-5
' 1-2*
of fore-limb to tip of middle f i n g e r ...............................................................................
2 0
5-2*
2 0
„ of middlo finger ....................................................................................................................... 5-24
• „ of foot . • • • • 1 1 • • • '• * > . l-2 i
Length of ear . . , . . ■ • • • • • 3i
Breadth between eyes . ............................................................ 6:0
9-4*
„ head, over e a r s ............................................................................................................ 10-8
„ behind shoulder . • • • ■ • • • . * 7-0
The above table shows that while the larger individual had a slightly shorter tail,
they agree in other respects, allowance being made for the greater age of *, and this
harmony prevails in the bones, the measurements of which follow. The only differences
of form observable in the skeleton of 0, as compared with «, are the greater
forward curvature of the proximal end of the humerus and more prominent character
of the deltoid ridge. But we are met with the fact that the skeleton of 0 has
13 ribs, its vertebral elements being—cervical 7, dorsal 13, lumbar 6, sacral 3, caudal
20 forty-nine in all, while in « the normal number of ribs prevails with 6 lumbar
i Darwin records that Mr. Bartlett has observed that in all species of monkey known, in which the adults of
both sexes have strongly-coloured faces, the colours are dull and absent during early youth, and he remarks that
this likewise holds good of M. rhesus. This animal may, therefore, have been longer in reaching maturity than the
other, which seems probable from the circumstance that the occasional temporal flushing and enlargement of its
buttocks was very much less intense. Mr. Bartlett has also observed that the naked surfaces extend with age.
Descent o f M an, vol. ii, pp. 310 and 377.
vertebrae and 18 caudal = only forty-six vertebrae. The skeletons are ligamentous
and perfectly entire, even to the last caudal ossicle. The 13th rib of the former
specimen is a short straight bone, an inch in length. There are eight true ribs in
each. In 0, the mammillary processes appear on the 11th dorsal and in « on the 10th;
in the former the anapophyses first show themselves on the 13th dorsal and gradually
decrease in size from the 3rd lumbar vertebra, these processes following a
similar course in the twelve-ribbed specimen, i. e., commencing on the 21st segment.
The caudal vertebrae gradually increase in length from before backwards as far as
the 8th, beyond which they again shorten. The last trace of the neural arch occurs
in the 5th caudal vertebra, on which the laminae are prolonged for only two-thirds
of its extent. In « there is a tubercular-like neural spine on the 1st caudal only,
but in 0 there is no trace of it. The transverse process of the 1st caudal has considerable
antero-posterior expansion, but in the succeeding vertebrae it gradually decreases,
and disappears on the 6th. In both examples, chevron bones well developed
occur first between the 2nd and 3rd caudals up to the 5th and 6th, beyond which
they do not extend, although a pair of hyperpophyses can be detected for some
distance backwards. In both these females, the manubrium is followed by seven
osseous segments terminated by the xiphoid, which is much longer and more expanded
in 0 than in a. The sternal elements also immediately preceding the
xiphoid are considerably longer in the latter than in the former, in which the total
sternum is 3-36, whilst in 0 it is 3*66. The manubrium of 0 is unsymmetrical,
being larger in its left than in its right half, to the former of which the cartilages
of the 1st and 2nd ribs are together attached, whilst the opposite bears'only the 1st
rib. The clavicle of 0 is a shorter and stouter bone than that of *, measuring
1*84 as compared with 2-08.
The pelvis of « has greater capacity and posterior breadth than 0, in which
the distance between the callosities at their middle is only *75, in a being 1*18,
while between the position of the ischial spines the pelvis of « has a breadth of
1*22 and /3 of 1*52. These little differences, however, can hardly be regarded as
more than individual.
These skeletons do not present any anatomical features which would entitle
them to be regarded as specifically distinct from M. rhesus. The existence of 13
dorsal vertebrae in 0 being associated with only 6 lumbar vertebrae shows th a t this
monkey, which in its external' characters differs somewhat from M. rhesus, is by its
osteology more allied to it than «, which, in its peripheral features, differs in no
respect from 21. rhesus. I have referred to the existence of only 18 trunk vertebrae in
the latter specimen under 21. assamensis, the Burmese example of which is also
distinguished by a similar number of trunk vertebrae.
In three skeletons of 21. rhesus in the Royal College of Surgeons in which the
tail is entire there are from 17 to 18 caudal vertebrae, the specimen No. 4991' having
the tail imperfect; but as the foregoing monkey 0 has 20 tail segments, the variai
See Quart. Proc. Zool. Soc. 1875, p. 562.